How to structure seller financing deal

[Sandy D.]

I own a five unit MF in Huntsville, TX on 10 acres.  I am a newbie and this is my first and only investment property.  Someone wants to purchase using seller finance so his daughter can live across the street from him.  How do I structure this deal when it still has debt service and rental income?

I bet any of you can offer some kind of guidance here and it will definitely help me - good, bad, or ugly.  I can offer number if anyone is willing to crunch numbers with me.  Thanks!!