purchasing a home with (non-contracted) tenant

[Marquise Crampton]

Hello. I am looking for insight on verbal contracts and how they may hold up in court. I am getting ready to purchase a home for an elderly lady. She is currently slowing her daughter an kids to live there and they pay the bills as they come. Mortgage, taxes, utilities, and maintenance. Now there was never any contracts made all just by verbal agree ment. And I'm not sure who's name the payments have been recorded under. The question I have is does the daughter have any legal rights as a normal tenant would. The reason being is she threatened the mother  to sue if she sold the house. Thanks in advance to anyone with insight