Any advice on what to do would be greatly appreciated!

I'm wholesaling a property that is set to close this Friday 02/15/13.
Back in December the Independent Executor of Estate signed the Purchase and sale agreement. He has already signed the assignment of the contract and met with the buyer.

While getting the title information together, the underwriters are requiring that the Executor's son-in-law and step son sign at closing and agree to shared proceeds.

Here's the dilemma. The Executor and the son-in-law do not get along, and for weeks now, would not sign the proceeds agreement. They wanted the other person to sign off first. Neither one wanted to meet in person.

Now that it's the last week of closing, The Executor of Estate is not returning calls or emails. He isn't responding to the title company either.

The Son-in-law wants to sell, but has been told by other family members that the executor isn't going to sell but rent out the property instead. So he's waiting for the executor to agree to his 1/3 of the proceeds and then he will sign.

At this point If the executor doesn't show up to the closing, is there anything that can be done to enforce the sell of the property? Would the other 2 sellers that are required at closing be able to complete the transaction without him??

Would enforcing specific performance be something I would have to have the buyer initiate as a lawsuit if it came to it??

Any advice would be great.