An open contract and Alzheimers

[Nat C.]

I have been in negotiations with 2 owners to buy their property. Suddenly they remembered there is an 'open' contract from 2006 when a church bishop was supposed to buy the property. They signed a contract however the bishop never followed through with the sale then he developed Alzheimers and then he was demoted from his position as bishop as he caused the church to become bankrupt and had signed multiple contracts for purchases he never followed through with.

The owners are concerned about the open contract. How do we move forward? The chances of getting a cancelled contract signed by the ex-bishop with Alzheimers is very unlikely.