Newbie question on rent to sale

[Jonathan Thomas]

Hello I'm new to bigger pockets and had a question. I have a house that I am renting to my sisters family. They are well off but are in a bind due to trying to sell their old house. they want to rent for a year and then purchase the house. what would be the best way to transfer ownership after the year? should it be a sale quick deed or what? Im trying to help but not lose money also.