Rent to own legal question in Texas

[Casey S.]

Just closed on a lower end house. Title was clear. Seller told me the current tenants never paid rent but he didn't want to deal with them. I went by after closing to post a 3 day notice. The tenants just called me saying they have a notarized rent to own contract signed between them and the previous owner and all of his receipts showing that they have paid every month. They claim to only have less than two years left to pay. It was obviously never filed at the court house or title would have caught it. I am going to meet with the tenants Monday to see what they have. Anybody know what kind of rights the tenants might have if their rent to own story checks out?