If I am understanding your question correctly, all that you would need to do have the buyer and seller sign an extension. It can be something as simple as "The closing date for the contract on the property located at **address** dated **contract date** between **seller** and **buyer** shall be changed from **original close date** to **new close date**. I would go ahead and extend it by probably at least a week longer than you need should another unforeseen problem come up that delays closing again, then you don't have to have another extension signed. I realize this is the obvious answer. If you have a specific situation that you are dealing with, it would probably be best to ask a Realtor or if you have a legal question, check with a lawyer. :) Feel free to email me if you have a more specific question via my website.