I don't really understand how money works, so I would be grateful if you could tell me if this will work out fair or not.
My mum cannot afford her mortgage. My brother and sister live with her, and she is signing the mortgage over to my brother. Presumably also putting him on the deeds of the house. He will pay all the mortgage, I don't know if she is making a contribution towards it.
If she dies, she leaves half the house to him, and a quarter each to my sister and I. She says she is stipulating that the house must be sold within a certain timespan after she passes away.
The names on the title deeds to the house have to match the names on the mortgage so you need to check that your Mum will continue to be named on both to protect her interest in the house. They should then hold the house as tenants in common which means that they will have "shares". So if they hold the house in equal share, ie. 50% each, he will have half and she can leave her half to you and your sister, ie. 25% each. But you do need to make sure that your Mum gets proper legal advice, independent to any which your brother is getting, to make sure she gets the result she wants.
The other thing is that if your mother is elderly and your brother is living with her, there could be all sorts of family arguments about him exercising undue influence over her... None of you want to go down that road, if you ask me!!!
And if he owns 50% of the house, say, she can't make him sell his share so you could end up going to court if he doesn't co-operate. Again, not something you want to do when your mother has just passed away...
she's not elderly, she's 53, my brother is 22 and my sister is 17 (and unemployed)
what concerns me is that my brother and sister have such a volatile relationship, that he may one day decide to have her evicted. My mum may not agree with this but if he has equal say over the house, he has equal say over who lives there, right?
What if my brother decides he wants to move out? She would have to buy him out and she can't afford that.
TBH, I suspect there is little you can do to control the situation - at the end of the day, it's her house, her choice, but I don't think it sounds great. Why can't she downsize to something more manageable?