Can you Trade first rent for Cash?

[Zachary Hite]

So need some advice, I have a sister that has never had a credit card and therefore no credit. She is having to move out of the friend's house that has been letting her live there free and cant find anywhere that will take her without a credit score or any rental history. 

So in the meantime I am looking at a deal that I am short of cash for but want to move on if things all are above board. She seems interested in giving the cash for this to go through but wants it paid back in rent to give her time to get a credit card and build up a score and even rent it afterwards potentially.

So is there any downside, will the lender protest? (Besides the obvious doing business with family issue)

-Zachary Hite