To have called time on my marriage. A family of two halves.

So if 10 year old gets invited to bowling party, it’s a no unless her 5 yo sis gets to go too?

I don't think OP will come back to this thread.

This thread didn't validate her as she expected so she stopped engaging.

And I doubt she'll divorce - I think she tried to blackmail DH with divorce threat and didn't expect him to agree. She'll try to mend things. Unfortunately for DH and his daughters.

Your mother needs to get a fucking grip.

Well done for prioritising your eldest child......the household set up sounds extremely damaging for her.

You said your stepdaughter and younger daughter receive advantages that you cant afford for your older daughter.

NO. Just NO. How have you created this ghastly situation? Your poor older daughter - this is grossly unfair and you need to equalise things. I will not say what I truly think about your parenting.

is your mother leaving your stepdaughter money? Does she see your stepdaughter on the same level as her bio grandchildren?
a very pertinent question! @GeorgeClarkefan if your mum won the lottery would she give your sd the same as you dd?

I can’t have one child doing stuff, meeting other kids as a result, being invited to things when the other child does just one afterschool club.

Your eldest is what, 10? Your youngest is 5. Your eldest isn't going to be invited to things with 5 year olds. There's an age gap as well as a privilege gap and you can't just force your eldest into your youngest's social life. She has to develop her peer group independently of her sister. You're thinking this is your youngest's job and it's just not.

My stepdaughter doesn’t live with us.

And when she's around, you expect your eldest to be there. Have you ever thought about giving SD and her little sister and your husband their own time? Or giving your MIL time with her youngest granddaughter without your eldest around? Again, your SD is 14 or 15 so another age gap and she's not there to spend time with your eldest. She's wanting to see her little sister without dad's wife and daughter there constantly.

My MiL is actively getting rid of money but husband isn’t getting any just his sisters.

And now you're filing for divorce. There's no money to split in the foreseeable future and he's resentful that he's been disinherited and bypassed.

He says that he has been disadvantaged in relation to inheritance etc because he has a stepchild and not once asked to divorce but I now have, over a hobby.

Is your mother leaving your stepdaughter money? Does she see your stepdaughter on the same level as her bio grandchildren?

he feels that rather than have one advantaged I want both disadvantaged.

It seems like you actually want your eldest to have everything your youngest does but given the realities involved, that's unreasonable. But if you pull your youngest out of lessons to placate your eldest, yes, you would be depriving her to soothe the jealousy of your eldest.

Elder one is completely distraught and my life is not worth living.

So she's making the home and you miserable because she can't do the same activity. She feels entitled and jealous and I think you've fed that by not being very clear about the financial facts and her expectations. Youngest gets a gift from her dad's relatives. That's it.

What do you think your eldest is going to do when your youngest leaves to go for her custody time with her dad?

She’s just 9 yo though. It’s heartbreaking for her. I couldn’t do what you suggested. I’d have to shield her, somehow, from being left-out.

If I didn’t leave, I’d definitely get a second job to fund these luxuries for her.

Divorce is the right option for OP because 'D'H could then do as he pleased for HIS girls. It's clear that resentment exists and is growing for both of them. OP is trying to manage her two children who live under different circumstances, under the same roof. DH is trying to manage his two children who live under different circumstances, under different roofs. The OPs eldest child will face her disadvantages more directly, more frequently. It's not just a hobby for OP, it's likely that she cannot willingly put her kid through another (weekly) reminder that she's poorer than her sister. The DH doesn't have these concerns, mostly because his eldest DD is richer (via her mum), but his youngest DD doesn't have to experience feeling like the poorer relative because she doesn't live with her sister and her dad's family give her a good life.

OP's goals are not the same as her husband's.
It was a mess from the start, made worse by their weaker financial circumstance. OP is the sole advocate for her eldest child's wellbeing, against a family who want to draw thick lines between their blood vs not blood. The couple will always be at odds with each other, best they start considering that they aren't compatible. Maybe compromises can be made.

Youngest DD is caught in the crossfire and it's everyone's fault. She'll definitely be affected emotionally as she matures to understand it all.

The ex wife is the one living with less headache/concerns it seems. The luckiest of the bunch.

How will leaving the situation protect her eldest? Her eldest now has a half sister, who will always have difference life experiences and opportunities? All leaving will do, is take away, what sounds to have been, a pretty good father figure in her life. A man who treats her as his own, even if his family don’t.

OP needs to teach her daughter that fair, isn’t always fair to everyone. Life isn’t always equal. She needs to teach her resilience.

I more meant inheritance by big money.

You have a very random and confusing writing style which I'm really struggling with. I'm guessing that it might reflect all of the upset and confusion that you are feeling.

Could I suggest that you take your time and consciously write down what is going on, proof read it as dispassionately as possible, edit and keep doing this until the situation is crystal clear?

I really think that this will help you to see more clearly what's going on, what the main issues are and possibly what can be done about them.

I think once the children reach a certain age and understand the value of money, there’s no requirement to pay for each of them. Young adults will most certainly get this.

But children, 5 yo and 9 yo do not understand the first thing about the value of money and therefore simply feel left-out with no real understanding as to why this is, even if told sister’s grandmother is paying. They assume they are just not-liked and it’s hurtful to them.

OP needs to find an extra source of income to keep up with the Jones’ or possibly leave the situation completely, to protect her eldest.

From reading the OP other threads she seems very grabby & self centered

Maybe the grandmother can clearly see that if she gives her son an inheritance it will be spent on the OP and her daughters cutting out the stepdaughter

That if her son died and the wife (OP) inherits what was his money OP clearly won’t give any to her SD and this is pretty common to be fair

so granny is quite happy to cut her son out and give directly to her grandkids to ensure that they get any inheritance

Granny knows that her son is weak and the OP won’t be happy until her eldest is treated financially the same as the other kids despite being told it’s never gonna happen

I’d be really interested/nosy to see what % of people who say they treat all the kids the same do so when it comes go big money. I doubt it’s no one but I’d assume it not very high.

Exactly
my son has inherited from his grandparents a very large amount
he also had private school money for cars leaning to drive gap year and other stuff all paid for by grandparents

it would have no more entered my parents or his other grandparents head that they have to split it 3 ways to included 2 step children who they don’t really know

Or that they can’t give my son money or gifts because it’s not fair on his step brothers

And although DH and I don’t have a joint child I wouldn’t expect my sons paternal grandparents to match everything they gave to their grandson to also give the same to a half brother
That would be very selfish and entitled of me if I thought that should be the case

No one will pay thousands for their stepgrandchild- to fund university fees or house deposits.

I think they don’t have it, MIL isn’t saving them money as such because they didn’t have the money to spend on the hobby.

There is mention of an overdraft & both of them being down to little cash (I think).

Op I think your naive to think step grandparents should pay for your eldest technically she’s saving you money by treating your youngest so why not spend this on your eldest. Blended families are a nightmare for non blood relatives just because your dh took on your dd doesn’t mean his family have to. Your eldest is disadvantaged because of you. If you think divorce is for the best then do it but your eldest will still miss out on anything your youngest gets. You have to accept that dh parents are not obligated to pay for your child. Your eldest needs to know that dh parents are not her family.

The youngest has 2 sisters, not just the OP's eldest. She'll be expected to watch her sister by her father do a hobby her own grandmother is willing to fund for her, in order to placate her mother's daughter. That is not any fairer. The OP should have figured all this out before blending her family.

OP, you mention here that your step daughter only really wants to see her dad and your youngest (her half sister). It is sad that the 'blending' hasn't gone totally smoothly, but try to have some empathy that your DSD might well feel jealous of your eldest daughter living full time with your DH who is DSD's actual dad.
So really it's understandable that your DSD might want some time with her dad, without your eldest (or you) being there.
That is the time for you to give your eldest some special quality time - just you and her. If you haven't got spare money, don't worry - do something with her that's lovely and special and free! Something that she'll enjoy cos it's just you and her. (I'm not sure of examples here as I don't know her age, but I'm thinking baking... craft.... movies....facepacks... I dunno, but I truly think that kids remember and value the simple fun times of having a quality connection with a parent, and the amount of money involved is irrelevent.)
Hard as it is, some effort needs to be made from all the adults in this situation to support the needs of the kids involved.

Thank you!

@Mumofoneandone cruel for not accepting being forced to pass her money on to a young adult who is no relation to her?

https://www.mumsnet.com/talk/am_i_being_unreasonable/5436923-step-daughter-versus-daughter-mumsnet-bingo

I can’t seem to find the thread about the Disney trip or OPs DM encouraging / forcing her to get married.

What a cruel woman your MIL is! Why can't she be grateful for a bonus granddaughter?!
Well done for standing up for your eldest daughter - she needs to know you'll always have her back.
I have 3 adopted cousins and never thought of them as anything other than my cousins. (Only really in contact with 1 of them now but that's nothing to do with the adoption......).
My 2 children have 'adopted' grandparents - who absolutely adore them and treat them the same as their own biological grandchildren. This is simply close family friends........