AIBU to resent FIL expecting DH to provide for his sister?

Sorry OP but this would be a deal breaker for me. Your FiL is a nasty, manipulative old sod and your DH is enabling that to the point of prioritising his sister over you and his children. He needs to grow a spine and tell his father where to get off, then change his will in favour of caring for you and your children in the event of his death.

YANBU. DH needs to ignore FIL and put your DC and you first in his will.

Presumably SIL will inherit from FIL anyway?

If it’s a nominal sum, who cares?

FIL will not let you know what is in his will, but thinks he can dictate what is in DHs will. No.

It sounds like FIL doesn't plan to leave anything to SIL. If he fully owns his large London home it sounds like there would be a lot for SIL to purchase a home.

My DH has an older sister, also in her 50s, single and childfree. If my ILs asked something like this it would be flat no! Like you SIL, she is capable of looking after herself. The only 'providing' we will do for her is ensuring that she always knows she is an integral part of our family lives and that we love having her around.

This….

I think your DH has misunderstood his father.

I suspect your FIL’s will leaves everything to your DH with instructions for him to “look after” his sister. Horrendously paternalistic, but seems likely. Possible that FIL disapproves or SIL’s life choices?

He's being ridiculous and your husband needs to tell him, I wouldn't have much to do with him to be honest, let him 'be the head of the family' without family around him...

If my DH did this for his able bodied but useless sister who is crap with money and is always trying to get sympathy I would divorce him and have told him this. I mean my MIL gets on my nerves but once she has gone I expect SIL may try and rinse us.

Your husband’s first priority is his own immediate family. Sounds like he’s rather spineless. His dad doesn’t even need to know what’s in his will, he can just be evasive on the subject.
In any case I’m pretty sure if you got decent advice on this they would tell you this is a bad idea. It rarely makes sense to direct inheritance in any direction other than to a spouse or children, due to IHT.

This is a bonkers thing to do in your wills. It makes things unnecessarily complicated. Mirror wills is the way to go. When FIL dies it's up to him what he wants to do with his estate. It is not up to him what you do with yours.

how would fil even know what your will contains?

if he means he will leave everything to your DH and rely on him to do the right thing by his sister by providing for her after that then.i can sort of understand even though its barmy. but prior to fils death your wills should provide for you dh and dc only.

I hope youve taken legal advice to protect your dc from bonkers fil and dh if you die first

Yabu to blame your father in law for this - has your husband no autonomy?? Why doesn't he do the normal thing and tell his father to mind his own business?

… taking it to mean that in his own will, he will leave a not insubstantial sum to his sister
… To clarify, it’s a nominal sum that DH is leaving to his sister, not a percentage, so it will degrade with inflation, over time.

Which is it?

Are we talking about a life changing sum that would significantly reduce your children’s lifestyle……. Or what?

Is he asking your dh to hand his share of the inheritance to his sister? I think that's what MIL was suggesting when she said the same to us. Dh had already decided to do that anyway.

Your DH is acting like a wet lettuce. I would have told him to man up and tell his father that HE should give Sil whatever he wants now and leave everything to her in his will. Then, if sil is in need (lacking food/housing) you will obviously help her out.

This ^
its very ridiculous of him to put his adult sister who has job and able to live independently ahead of his own children and his wife.
I also can’t understand why your DH should leave something in the will to his sister. I can’t see the logic. Now FIL is here and can help her. After FIL’s departure she will have her inheritance I presume. If FIL is worried about care home fees he should help his daughter now. What your DH’s will got to do with it?

By the way FIL is just playing games. If he wants to provide for his daughter when he is not here - he can do this now or later in his will. Otherwise he can’t have a say in things when he is not here. And he can’t have a say in how your family distribute its money. He needs to learn that he can only control his own affairs and your DH needs to learn that only you both control your own affairs.
By the way I wouldn’t count on sister being fiercely independent in say 20 years. When it comes to money people usually show their natural selfish side.

DH is an incredibly moral man and has sworn to this, taking it to mean that in his own will, he will leave a not insubstantial sum to his sister before anything goes to me and our children in the event of his death.

you can'T control what is in someone's will. However i would be pointing out to DH that the FIL should be providing for his own child, and that he should be providing for his as a priority, then you, then if he wants his sister. And that if he carries on with his plan, you will be putting steps in place to ensure that if you predecease him, your own DCs get everything.

Nip the "head of the family" nonsense in the bud.

I cannot get my head around your DH changing his will in order to help buy an independent grown woman her own flat, at the cost of providing as much as possible to his own children.

Your FIL is unreasonable, but your DH too.
If it came to it, how would your SIL actually feel signing for a new flat with money that any sensible person knows belongs with her nephew's?????

Your FIL is a nasty, shit-stirring man.

Your DH is a spineless idiot.

Sorry, I would be absolutely furious and throw a grenade in and tell SIL about all this madness. Might even tell the children and then divorce this fool.

How old is he? Do you have decades or a few years of this nonsense left, realistically?

Have you actually said to your husband:
'Your father is asking you to take on this supposed duty from him, but he isnt doing it himself right now, why do you think that is?'
And what did he say?

This isn't about some weird and sexist notions of being 'head of the family', if that was the case, your FIL would be making appropriate arrangements for his own children and that would be the end of the matter.
This is about control.
Your SIL is the excuse, perhaps your FIL just wants to feel powerful and this is his last shot. Your husband's 'moral code' is being abused given that his most important duty is to his wife and children, his sister's welfare is a secondary matter. She is a fully functioning adult living her own life and she is in her fifties. If her own father hasn't thought it necessary to help her out financially that is the end of the matter. Presumably within his will he has made provision for her? If not, it demonstrates that his use of terms such as 'head of the household' is just to manipulate your son, with bogus claims of the patriarchy. Btw if you tell your SIL about her father's demands what will she make of all this.....You should remind your husband of his wedding vows and for good reason, they didn't include promises to his father.
Your FIL is manipulating his son by demanding that he act contrary to the best interests of his nuclear family. How will your children feel about their father, if your FIL's wishes are implemented.....how will you feel about your husband if he prioritises his adult sister over his dependent children? Your FIL is sowing a lot of division within your marriage, he should never have uttered a word about your wills.

Also this!!

I’m confused. Why doesn’t the FIL just leave his estate to his 2 children equally (or a bigger share to her) and then SIL is “taken care of” anyway? Why does your DH need to be involved?

“taking it to mean that in his own will, he will leave a not insubstantial sum to his sister before anything goes to me and our children in the event of his death”

This is outrageous. If his DF thinks that SIL needs “looking after”, there’s nothing stopping him from leaving her his whole estate - I assume he’s living in a house he owns? But your DH’s first duty is to his wife and children, and I would be letting him know that in no uncertain terms. OP, I would be livid if my DH were to write such a will. Your DH is “the man of the family” - his OWN family, which is you and the DC. I would be getting him to change his will pronto, because none of us know what the future will hold. A friend of my DD’s died recently in a freak accident, so your DH’s responsibility is to ensure the future of yourself and his DC.