AIBU to tell DH to split his inheritance with his half siblings?

Sure, because historically women have always been in a position to protect their financial situation. How old, OP, was the mother - was she even the generation who could get a mortgage or a bank account without her husband’s say so?

If you are in a second marriage and you want your (not husbands) kids to get something you HAVE TO PUT IT IN YOUR WILL. You cannot trust your husband to do it and not change their will after you’ve passed. It’s human nature to favour your biological offspring, and who knows how long it will be before your 2nd husband passes, anything can happen in that time

It was his mums wish to leave each of her 3 children a share, his dad wanted to leave his share solely to your DH…
Morally your DH should give his two siblings one sixth of the estate value each.

I hear this happening again and again when people remarry, the remaining spouse not respecting their deceased spouses wishes to their children from a prior marriage. Why on Earth don’t people leave their share to their children rather than to their current spouse is beyond me…
it’s really so unfair on the elder children and totally disrespectful to their mothers wishes.

Your husband saying no because they’re older and own their houses…. No doubt they’ve worked bloody hard to own their houses.. do they not have children that they may wish to help out? - his mothers grandchildren!

Your DH sounds very selfish and unkind

DH lost both of his parents quite young, when he was in his late 20s. His parents were both on their second marriage. He was adopted but only found out on his dad’s death.

His mum had two biological children with her first husband. They are in their late 50s, so much much older than DH. He sees them maybe 2-3 times a year, but growing up he didn’t really see them for a few years at a time. They’re both nice people.

When his mum died, she left his dad all of their property/money. She wanted her half to be split amongst her three children.

When DH’s dad died, he left everything to DH. It’s not an enormous sum but includes a very small flat in Kensington so it’s an estate of £1m+

DH’s siblings have now come to ask if he will be giving them their share of the estate. That is, for the mum’s half, split between them. DH doesn’t want to give them anything as it was left to him. He also says the money is more useful for him than them as they’re retired or about to and own their own houses outright.

If she was if sound mind then his mum could easily have made provision for the siblings if she wanted to. I wonder if she secretly favoured her youngest child?

I suspect your DH is thinking it’s not much of a loss in terms of the relationships if he sticks to his guns and doesn’t give his siblings any money as he’s not close to them. I don’t blame him.

Unless we are told where the 'information' of mother's wishes comes from, as she didn't make a Will to confirm them, there's no moral case either.

DH lost both of his parents quite young, when he was in his late 20s. His parents were both on their second marriage. He was adopted but only found out on his dad’s death.

His mum had two biological children with her first husband. They are in their late 50s, so much much older than DH. He sees them maybe 2-3 times a year, but growing up he didn’t really see them for a few years at a time. They’re both nice people.

When his mum died, she left his dad all of their property/money. She wanted her half to be split amongst her three children.

When DH’s dad died, he left everything to DH. It’s not an enormous sum but includes a very small flat in Kensington so it’s an estate of £1m+

DH’s siblings have now come to ask if he will be giving them their share of the estate. That is, for the mum’s half, split between them. DH doesn’t want to give them anything as it was left to him. He also says the money is more useful for him than them as they’re retired or about to and own their own houses outright.

Well the good news is that you can give them their share.

File for divorce. Take 50% and you can redistribute.

His mum Should have stated in her will that half to her husband, the rest to be split 3 ways between her children. Did she have a will, if so what did it say and was it honoured.

But it’s not the mums estate, the mum left her estate to her husband at which point it became his money, he could’ve chosen to spend the lot on cruises or lottery tickets or fast cars. The ops husband has inherited his father’s estate and unless either of his parents left wills to the contrary then that is what they wanted.

So the first sounds similar to “Tenants in common” and the second to “joint tenants” that is used in E&W.

I hope the subs take him to court over this. If I was them I would be tempted to more for the injustice than the money even.

The first question a solicitor will ask is 'What evidence do you have that these were your mother's wishes?'
(Or possibly the second. The first question might be 'How much money do you have to throw at this?')

Land and houses can be owned equally or equally and to the survivor. The first means that each owner can leave their share to whoever they want; the second means it passes automatically to the survivor and can't be altered by a will. There are valid reasons for choosing either.

"In Scotland, that's not the case. We have no concept of "joint tenants" where property is owned, not rented. There might be a survivorship destination but it's not always the case."

You are mistaken. In Scotland, a 'survivorship destination' is the exact equivalent of owning a home as 'joint tenants' in England & Wales.

The Scottish equivalent of the English 'tenants in common' is sometimes, rather confusingly, referred to as 'joint tenants' or, more often,as 'pro indiviso'.

If a property in Scotland is held on a 'survivorship destination' basis then the deeds will typically include the phrase that the property is owned "equally between them and to the survivor of them".

In contrast, for a property that is owned on a 'pro indiviso' basis the deeds will typically say that the property is owned "equally between them and to their respective executors and assignees".

It IS an enormous sum.

Your DH should get financial advice and split their mum's estate by 1/3 to each sibling.