Open Question: What should I do to protect my interest in property Iam purchasing.?

The lady whom I have been paying for some property has just passed away. She left no will. She has a son and several grand children. I have three remaining payments left on a 20 year owner financed note. How do I ensure that I can get the tiltle to the property in a reasonable time. How can they or her son get the right to do the paperwork and receive the last payments that will benifit us all?