Protecting inheritance

[DaveOrange]

Brief scenario

Widow living in her own mortgage free house.
Plenty of savings and growing as her pension is far greater than her outgoings
Her will states her estate to be split equally to her 4 grandchildren and she wants this to always be the case.

All good so far........

She has now met a widower and is talking about him selling his house and moving in with her.
He has family including 10 grandchildren who are all in his will.

Some concerns

Would he have any claim on the house or her savings?
Would his family have any claim on the house in the event of his death?
If he out lives her what happens to the house?
Do things change dramatically if they were to marry?
What other concerns would you have?

Thanks

[DaveOrange]

Op here. I should add that I am not one of the beneficiaries before I get flamed as a scrounger. I am very pleased that she has met someone who makes her happy. Her 1st husband died 6 years ago after being married for 52 years. My concern is that the 4 grandchildren aren't disadvantaged in anyway and indeed she has asked me to make sure that this doesn't happen.

Thanks for the advice so far.

[DaveOrange]

Some good advice guys, many thanks. I will be arranging an appointment with a suitably qualified (STEP) lawyer.

PS BV, I could do with an inheritance of some sort, those Interceptors aren't cheap to run are they?