Mum has denied DSis’s disability her whole life - I don’t know how to deal with it anymore

The person you need to talk to is your sister. Tell her everything you have said here. Mum is irrelevant now but you can help your sister to see things differently.

Your mum didn't do her best and I'd be pointing that out to her in fairly bald terms next time it's said. Ignoring a medical diagnosis when your sis was a toddler is not anyone's "best". It's neglect

Just a thought but maybe your mother felt that to acknowledge her daughter’s disability would reflect on her? Maybe she felt ashamed? Or that she would be somehow judged for having a child with a disability? I am by No means suggesting that it is OK for her to have done what she did! So research how you can alert someone who could help & advocate on behalf of your sister. Though it could become a legal platform if your mother is deemed to be “abusing” your sister by denying her help/support. Seek legal advice!

What does she actually need that she doesn’t have?

GP can refer for physiotherapy assessment for example and will they also provide mobility aids eg stick(s).

Counselling for your sister would be helpful.

DM is unlikely to change which in many ways is irrelevant now.

I remember my Mother happily telling me - to my face - how someone with MY medical condition completely ruined her friend’s birthday dinner (my Mother was attending).
They were dining at another table and an ambulance had to be called.
Apparently it was very upsetting and embarrassing for my Mother’s friends AND my Mother. Totally spoiled the meal.

Again, a lot of the denial fell on the sword of ‘didn’t want me to be treated any differently’.

It wasn’t until I got married that my husband encouraged me to empower myself and basically not just take the medication, but find out something about the medical condition I had and if any support (there was!) was available.

DSis is an adult. You need to dissuade her from the ‘not making a fuss’ mindset that your mother has instilled. I apologise for not putting the MN abbreviation DM but what your Mother did to your DSis doesn’t seem much of a ‘darling’ thing to do, to me.
She isn’t ‘making a fuss’ she would be applying for/claiming assistance that she has every right to.
Is there a support group for her condition?
It might do her good to be in contact, even online with others who have support, so that she can see this is normal for others like her.
Basically, that was how I started to find out about things. I joined the main UK support forum.

I wouldn’t worry about making your Mother feel guilty for the past. You and your DSis can do this without her. How your mother feels about what you achieve is her problem.

I wish you both the best of luck.

I would like to believe the mother is a strong example of someone who simply cannot accept hard truths so cannot accept the disability, therefore she makes up her own version of the truth. Denying the truth doesn't change the truth, it just make you less able to deal with it. There were cases of people dying in hospital with COVID who refused to accept they had it, same thing.

Times were not "very different then"!

My son is about the same age as the Dsis. He was born in 1990. He went to a mainstream school had good treatment and good care. No one thought any the less of him or me because of his disability. He was in the new world of openess and understanding of those with different abilities. It was very similar to how things are now!

This.

There's obviously a lot of denial going on there, and no doubt some underlying guilt that the mother herself has somehow caused it. Times were very different then, all the stigmas and lack of support and understanding and that feeling has carried on over the years. That can go either way - head in the sand or determination to do the best for her. My son was the first in our big family to be born with a disability. It took a lot of patient explanation, especially to my Mum who was so sad and afraid of the future for him. I know it's not quite the same as your situation but just that it can be a bombshell within a family.
I wish you both all the very best. She's very lucky to have you.

My sibling refuses to accept my parent has dementia. When she speaks to her on the phone she asks the same questions over and over. Medical people say she has dementia. Twice she has been in a dementia home once after hospital, another for respite. She still denies it 'she is dehydrated, she is tired, are they eating enough vegetables' etc.

They were the same when I had a condition. 'I don't think it is'. Even when I had an operation she said they had got it wrong.

I don't know if it is bloody mindeness, narcissism or that she is a comprehensive teacher of year 7's telling kids what to do all day long and 'she is always right'.

It is annoying and I feel your pain.

You and your sister need to think about the difference between equality and equity.

Equality 🟰 treating everyone the same
Equity 🟰 treating everyone in such a way that they can reach their potential.

Your sister achieving equity is not “making a fuss”, it’s living your best life.

And if your mum has something to say about that, shut her down straight away. “Not your decision anymore, Mum” and change the subject.

Just ignore your mum and get on with supporting your sister. The fact that she doesn’t live with her is all you need. Put your efforts into researching how to help your sister and encouraging your sister to accept help. There’s no need for your mum to know anything about it.

I knew a mother who was also a nurse and she was very tough on her child with a disability ( I believe it was CP)

she was NOT abusive. She simply didn’t want her child to be weak and deodenent. She didn’t want her child’s potential for growth and inference to be stifled by pity, mollycoddling.

Some may disagree but she was doing it out of love for hire child who she knew was capable and would be on her own after her mother was gone.

many people are never allowed to reach their full potential due to over protecting Molly coddling and helicopter parents

Since you are not being specific about the disability it is very difficult to understand.

You can’t expect anyone to form a reasonable opinion without more info.

Your DM neglected her child and now your DSis is suffering and not getting the help she's entitled to. Your priority should be to help your DSis and not worry whether your DM will approve or not.

I don’t have a neat answer but can tell you about a friend with severe disabilities whose parents were the same. She is really brave and intelligent and went to university, met her wonderful husband there and they are a delightful couple. With assistance from her husband and support workers, she gets out and lives life fully. Her parents still live a few miles away. Now that she is an adult, they cannot insist that she is not disabled but they do act like she only just became disabled, pretending that she was fine before. It’s really odd. I think they tell themselves that they are responsible for her «can do» spirit and pat themselves on the back for making her so strong.

I daren’t criticise others’ parenting too much as none of us is perfect. At the same time, I see the psychological damage a lifetime of being gaslit caused. There is a fine line between encouraging independence and flat out cruelty and her parents crossed it. While my friend somehow made it through and is thriving (albeit in frequent physical agony), it could have turned out very differently. Support from certain other family members and friends helped her survive and move away from what was an abusive situation. Your being there for your sister will make a huge difference, I’m certain.

Think this was very common. My cousin had learning disabilities and his parents never mentioned it. It was only when he very sadly died in midlife and his sister was talking about him that this was mentioned. Attitudes change OP. Your Mum probably thought she was doing the right thing.
Please do support your sister to get the counselling and support she needs X

Your mum is probably never going to change. Best thing is to accept that. But your sister is absolutely entitled to the support she needs and to have her disability recognised and assessed for support - that is enshrined in law. Speak to your sister and see what she wants - its not up to your mum. Your sister is engigled to a local authority assessment under the care act 2014 regardless. That is the first step - contact the local authority for an needs assessment for care and support and support your sister to get this done. Best of luck.

I know people of different ages including child who had/have a parent who played down their disability. The disabilities are a range.

Playing down means lying and misleading doctors, other healthcare practitioners, teachers and others who work for the child about their child's problems plus the help and adjustments that they need. This includes in the worse cases saying their child doesn't suffer from certain symptoms of their condition anymore then l cancelling appointments with particular specialities, and not giving prescribed medication.

One of my friends who works in healthcare told me years ago that she deliberately attempts to get children over 8 to speak for themselves and if she decides they are Gillick competent she will ask their parents/guardian to leave the room briefly. I've since found more practitioners if they can - so they have a nurse/student/other employee in the room - do this.

Attitudes depended on the disability, your cultural background and where you lived in the country.

So for example for some cultures being deaf was accepted so help at school was accepted but for others it wasn't Those who didn't accept then used the examples of poor treatment and practice to stop their child recieving the help they needed.

What are the activities that your sister struggles with and how can they be adapted to enable her?

What your mother has done is abuse. Your poor sister and poor you. I really hope you have both got good counsellors.

OP your mother should feel guilt. It’s normal and natural to feel guilt when you have done something that’s very wrong.

'My DSis (mid-30s) has a disability that affects her mobility and some aspects of daily life. It was diagnosed when she was a toddler, and she’s always had medical support for it. But DM has spent her entire life pretending it doesn’t exist.'

Sorry but I am confused by the above? Firstly who was it that diagnosed her disability, the doctor maybe, and what 'medical support' has she 'always had'? 🙄
My confusion is how your DM could possibly totally ignore an official medical diagnosis and/or the consequential 'medical' support' whatever that might have been or still is?
It sounds not only an odd way for your DM to behave although maybe she saw it as some sort of failure on her part, but I can't imagine how it was even possible for her to do this indefinitely even though you have done your best to challenge her over it?
I suppose what makes it more difficult to understand is not having details of the actual disabilities but I do appreciate why you might not feel it appropriate to disclose this information. 😥

I'm going to be a bit blunt because this is somewhat triggering. My parents were told I needed an operation on my lower back when I was pre-teen - I was at the consultation with the surgeon and remember it well. They weren't keen, so took a "wait and see" option that they squeezed out of the reluctant specialist. But they didn't wait or see - they just bunged me painkillers. And I'm 50 and have taken codeine every day for decades. Truth was, judged against many other episodes, they just couldn't be arsed to have that disruption in their lives. They'd give anyone a load of old guff about not wanting to disrupt my schooling etc., but truth is that they could not be bothered with the disruption. I have tons of material to back this up and they managed to ensure I was landed eventually with three disabilities, not just the one. Oh yes, I know what that neglect can do.

I'm not bitter, though. I've worked all this out for myself (built my own narrative), but both my parents had shitty upbringings themselves, they were isolated, my mother had autism... They didn't go out of their way to be nasty on purpose. I have come to a sort of peace that is only disrupted when my father says something twattish from time to time. And then I spend a few months reminding myself that he's an emotional vacuum and then we totter on again.

The thing is, this unpicking took me years and years, and I wanted to do it - I was driven. I wanted to feel better about the neglect. The problem here is that in essence you're asking your mother to do this now and she doesn't even want to - I was fully invested in working out all this shite! She has her narrative and she's sticking to it.

Resultantly, I doubt you can change your mother's opinion. She'd have a whole deck of cards crash down around her ears to change her position. I very much doubt your mother even understands why she really made the choices she made, so you're pulling on a long thread there. Instead, I think you're just going to have to soldier on with your DSis. But you are there for her, which is absolutely marvellous. Many of us neglected kids are only-children because, guess what? Our parents had a go and realised pretty damn quick that they weren't cut out for the endeavour!!! Your sister has a wonderful gift - that's you - and between you she will feel validated. People who have never had a hidden disability won't understand, but having others validate that you aren't tickety boo is half the battle - that's when you can start to ask for what you need, have the confidence to do your own research, even tell people what you're going through. You might try Quora to learn more about the condition - I cannot guarantee the quality of content for her condition, but for all of mine it has been brilliant and I've learned some really important things on there from people around the world that the NHS does not know.

Do you think that your DM is helping your DS to appear less vulnerable to people? It may not be pretending. That calls for the operation of her mind, and no one can know what that is.

Your DS has to go through life with a disability which may or may not be obvious, but believe me, there is an art to appearing less vulnerable, and one which must be mastered, because life isn't easy and people take cruel advantage of someone who is disabled.

So long as the people near her know her limitations, and she has the right treatment from her GP and other medical people she needs to treat her, it is better not to appear vulnerable: for example, walking splints can be hidden by long skirts. She could - if she hasn't already - join SCOPE and learn about appearing not to be disabled.

It isn't easy. On the one hand, you need people not to expect too much of you, but on the other hand, when meeting new people you don't want them to see you first as disabled, and second only to your nature.