Purchased 1/2 a Duplex and owner already converted duplex into Single Family in DFW

[Rav Ram]

Can anyone help with ideas on what to do with this scenario that is occurring in Tarrant County Texas. This is a friend of mine's property.

John purchases a priority that consists of half a duplex prior to a tax sale directly from a seller. Each half of the duplex is marked with a separate address and there are two sides. Unbeknownst to John, 5 years prior to his purchase, the other side of the duplex was purchased by Jose through owner finance and Jose converted the house to a single family home. The reason Jose converted the house was because an unscrupulous prior owner advised Jose that both sides of the duplex were his.

It's not Joses fault and jose is a good family man who is an illegal immigrant afraid of suing the seller. But now the buyer is stuck!!!

Any thoughts on what to do.