Owner financing with mortgage

[Dwight Rhodes]

Good afternoon all,

I'm currently working a deal with a homeowner in NC to purchase her home via seller financing. The problem is, she has a mortgage/lien of about 12k and she's selling the house for 40k (ARV $55k). The price is negotiable and the comps averaged out to around $30k. The property sits in a D class neighborhood so the rent is going to be a little lower. Actually, what she is currently paying on the house is about the amount of rent that I could fetch ($650).

How do I package this deal? She is willing to work with me, but I have no clue how to ensure the lien/mortgage is taken care of contractually. Please help!