How does this work?

[LadyGAgain]

DSis husband left a few months ago. No warning. Just came home and his stuff was gone. He's pushing for a divorce. She's in no rush (mortgage free so gives her time to save some money).
DM has inherited some money and wants to pass some onto DSis by a deed of variation. This has to be done within 2 years of inheriting. Her worry is that DSis STB ExH would be able to take half as they are no divorced/financial matters not yet settled.
Is this the case? Is there anything she can do to protect this money?
Thank you.

All assets go into the pot to be split between them. That includes the money she is saving and anything your mother gives her. If there are enough assets to meet her needs and her husbands needs there will be no need to dip into the inheritance. However, the needs of the family (i.e. your sister, her husband and any children) come first. If the only way to meet everyone's needs involves dipping into the inheritance she won't be able to keep all of it.

I suggest she gets on with the divorce.

Thank you for replying. There at no children.
So DM is best to not gift anything to her until their finances are sorted with no future claim clause. Everything else should be simple. Both DSis and her Ex inherited a similar amount each from separate deaths, paid equally into mortgage before it was paid off and bills etc. The only other variation is he has a sizeable pension and she has none but solicitors will take care of that I assume.
I will let DM know as she would hate him to get any of this money. Especially after his recent behaviour.

*There are no children

Definitely wait until after the divorce.

Thank you. All passed on.