Wanting to take over payments?

ok. im found a rent to own place from some ppl and they owe around $19k. so they go thru a company called vanderbilt. i live in north carolina. im guessing we would have to get approved with good credit to take over payments. now i have heard of some type of renters deeds or something to where we can draw up some paper to where i guess it stays in there name until we pay it off and it states they have to sign the place over to us. its a paper to protect us. then i wonder if we can be put down as a co signer to there agreement and make payments? idk much about that stuff but really want to own my place not pay rent forever lol. so if anyone can help me out with any ideas or what i can do thanks. mainly if anyone know what the paper is called i would need to do this and where to get it thanks.