Memorandum for land contract

[Cathy Wilson]

I want to buy my sisters house. It's owned and has no mortgage so we are drawing up our own unconventional agreement for payments. However, she doesn't want me to record the deed until it's paid in full. Will the memorandum and affidavit be enough legally to protect my rights? I don't want her one day saying she wants the house back. Any advice will be so greatly appreciated!