To tell my elderly father that I do have objections to him marrying his partner he met 6 months after my mother died?

Right - so OP’s mother’s poor will planning (sorry OP) should affect how her father now lives his life?

His will could already say everything goes to this woman! Or he could be planning on writing a new will immediately after marriage that leaves OP a fair and reasonable amount in a way that recognises that some of the money was her mother’s.

This is my belief as well. The thought that I could die and dh remarry and disinherit my dd is just horrendous. I really don’t understand these answers at all. If dh spends all the money, that’s different. If it all goes on care home fees for him, fine. But to be so reckless as to disinherit your child by giving your child’s other parent’s legacy to a stranger is awful.

You need to make an adequate will then

Sort your will out now, sort out how your house is owned and make sure half is in your name so you can leave it to whoever you want. Of course he can do the same so if he goes first you might find he's left his share to the salvation army.

Out of interest, how long had he known your mother before marrying her? Longer than 5 years, I'd assume by your assertion that 5 years is a short amount of time. Granted, by today's standards it is. Has your father made a will already? If so, marriage changes nothing. If your father hasn't made a will get, it would be prudent for him to do so - not for your sake but his own.

Your wording, incidentally, does lead to the following summary:
You don't object to your father's relationship as long as he doesn't marry, however remarrying is an insult to your mother's memory, and you're concerned about your inheritance.

My mother died several years ago. I'd be absolutely delighted if my father, who works hard and lives by himself, managed to find someone new as my mother insisted he do before she died. Would I be happy if he remarried? I couldn't honestly say, however he's made his will, and he's stated that it will NOT change, no matter what his circumstances. In point of fact, that doesn't actually matter to me at all. The only concern I gave him was how often I'd see him if he started seeing someone else, as I don't want to lose him at all, it's one of my biggest fears which I know will one day be realised. I wonder if your mother would want him to move on with his life or if she, too, would prefer he lives a lonely existence just to protect your inheritance. (This part of my response is based on the wording of your post, on which more emphasis, I felt, was placed on inheritance than your mother.)

However, you're not wholly wrong to be concerned, depending on your father's state of mind.

I presume your father has his wits about him, in which case the tale I am about to impart shouldn't matter, but...

A friend of mine's father wound up in hospital. By all accounts, it seemed he was completely compos mentis, however his nurse somehow convinced him to get a divorce. She then somehow managed to convince him to marry her. And then she somehow managed to get him to either change or destroy his will. This was within the space of six months. He died a short time after this, leaving his wife of 30+ years and his son with nothing, and there was nothing they could do about it because he had appeared to be compos mentis.

Now, an additional question for you: you say your sibling and you don't like her. Have you thought about why that might be? You've given the excuse to your father about ultimately being disrespectful to the memory of your mother. Is that the basis of this dislike? Or is there more to it which has nothing whatsoever to do with your mother? Might it be the way she speaks, the way she carries herself, the fact she's nothing like your mother?

Because of DH's experience and losing his inheritance, we went to a solicitor to draw wills up. If I died, the only way I can guarantee any heritance to our DC is leaving it to them at that point and not passing the estate in its entirety to DH. I can leave wishes that he leaves it to them but it's not legally binding.

This is so sad.

And if you flip it around to be from the perspective of the OP’s DM, or your GM, everyone would understand: “I’ve worked hard to build up a strong safety net for my beloved children. I now have a terminal illness and all my money is tied up in the house which will go to my DH. my DH has said when he remarries it is only right and proper that all the money then pass to his new wife and then onto her children, not to my kids, as this is what marriage means to him. AIBU to think this is wrong?”

People just need to write adequate wills. It’s not hard.

Yes. And she is absolutely right to be!

Of course if OPs DF wants or needs to spend his money then he should. But he also has a duty of care to ensure that assets (amassed jointly with OPs mother) are protected for future generations.

People will jump on me for this I’m sure but I would find it difficult to see a parent in another relationship, full stop.

Given their ages I don’t think you’re unreasonable to want to discuss all eventualities with him. Also given their ages I don’t really see the point in them marrying.

I don’t get this post at all. Unlike you with your dad, op wasn’t given anything in her mother’s will.

And sadly it is not uncommon for this to happen when someone has been widowed, or divorced. Men are only too quick to leave out the children from their first marriage by leaving everything to their wife, who in turn leaves the estate to a later partner or spouse or her children leaving the children from the first marriage with nothing.

What implications of a marriage contract specifically though? He can give her LPA without being married (and being married doesn’t grant LPA anyway). He can leave everything to her in his will without being married.

It’s not just his hard work, it’s her mother’s too and possibly her mother’s inheritance from her own ancestors.

The thought of me dying and everything going to a new wife and then to her kids, makes me nauseous honestly, it’s terrifying and a family tragedy.

There is no need to marry if you won’t be having children together.

The only way a marriage announcement should be made is. We are getting married and our finances are going to be inherited by our respective kids and we will be documenting this legally.

In the UK we are encouraged to leave estates to spouses for tax reasons too, which compounds te problem.

You don't need to be married to have LPA, I've got it for a relative and we aren't married.

The mother could have written her will to make allowance for this. Failure to so is poor planning.

I agree with pp you should have a talk with your dad about protecting your inheritance, why the need to marry again in your 80's, can't they carry on how it's been if no issues. I have a family member in her 60's still waiting for her inheritance, the second wife was only married to him for a few years before he died and she's been able to live in the family home that she didn't contribute to well into her 80's.

I agree

It's called sideways inheritance and its a real concern

On MN, people like to say it's grabby, but IRL, I think it's entirely reasonable to worry about your mother's assets passing to the children of your father's second wife

But marriage in and of itself doesn’t create happiness. The OP is not objecting to the relationship, she is concerned about the implications of a marriage contract. Significantly, the OP, and thus we, have no idea why he has decided on marriage and if he has thought through the implications.

Ans as I said in a previous post, I would hate to think that if I died after 50 years with my husband, everything we built up together, our home, our wealth, our art collection etc, could end up with some random woman’s children rather than my DC simply because my husband decided to re-marry rather than just be in a relationship without marrying.

So many men jump into new relationships shortly after their wives die. What the OP fears about being cut out of medical and practical decisions, as well as the assets her own mother will have contributed to is perfectly fair and valid.

My mother died on the Monday morning and I went to see my dad on the Thursday and I was introduced to his friend. She was shifty and left immediately so my spidey senses were alerted straight away. She attended my mother’s funeral but stayed out of the way. Two weeks after the funeral they met for a drink, 6 weeks after my mother died my father asked how I’d feel if they went away for a weekend together. I was absolutely floored, as was my sibling. Things went downhill between my father and I from that point, his girlfriend didn’t like me ‘interfering’ and over time she turned my father away from me, telling him he had to chose between me or her.
They have said that I was upset about losing inheritance but it definitely wasn’t, my father didn’t have a great deal of money. It was the fact he gave us no time to grieve for my mother and to find the new normal amongst us all.
We’ve not spoken for 10 years now, in the beginning it was like another bereavement, it changed me as a person I was broken for a while but I’m ok now. I’d have probably come round to things if he’d given it time. Up to you OP, 5 years is time, not 5 weeks like I had….

I agree with you OP and understand your worries. Neither me or my DH would remarry for that reason, we want our joint money to unequivocally go to our joint children, and would not put our finances at risk. I have seen too many disasters in the past from poorly drawn up wills and unwise remarriages.. It's not grabby to hope for something from your parents after they've enjoyed their own lives.
Could you talk to your dad about it? We wouldn't mind if our children did. And make sure they don't make mirror wills as they can be changed after the death of the first partner, something my step mother did when my father died. He would have been gutted, he trusted her implicitly.

But his wife will become 'His family'. She will naturally be involved in decisions around his health and finances.

You don't actually have an inheritance until someone has died.

Have you thought about things from your mums side? Would she have wanted your dad to live alone till the end of his days or would she have hoped he would find another partner?

Do you trust your dad to do what he thinks is right? He has chosen this lady to be his wife and if you don't accept that then you may find you lose your dad. He is an adult, as long as he is of sound mind then you need to butt out. He may want to travel the world with his new wife and spend what time and money he has left being happy.

There is no inheritance till he passes away.

I’d make sure my own will was written in a way to protect against this. Not leave a situation where my children have to argue with their father because they’ve assumed he won’t consider them in his will.