You are going to need 11 signatures at least twice, once on the contract and once on the deed(s).
This seems like it is one contract that depends on all the owners agreeing, it does not really sound like 11 contracts that are independent of each other. The contract can state the gross sales price and the sellers can sign a separate side agreement specifying how they will divide the proceeds of the sale. That side agreement can be incorporated into the escrow
One solution as to the contract is to put in a clause that says something like: This document may be executed in multiple originals, each of which is the original as to the parties who sign it. Or the contract can state something like: Counterparts of the signature pages may be combined to create a document binding on all of the Parties, and together shall constitute one and the same instrument.
That way, you can prepare one contract with all the sellers' names on the signature pages, and each seller can sign a separate copy so you do not have to send the same document to each seller one at a time.
As for the deeds, it would be quicker to have each seller sign a separate deed conveying his or her interest to the buyer. Otherwise you would have to have one deed signed and notarized in turn by each seller, and that would take more time than having each seller sign a separate deed.
I hope this information is helpful.