If they choose to continue offering Broker to Broker Compensation, have a seller sign TXR-2406 AMENDMENT TO REPRESENTATION AGREEMENT 

If they wish to negotiate Seller to Buyer Broker Compensation as Seller Concessions have the seller sign a new listing agreement RESIDENTIAL REAL ESTATE LISTING AGREEMENT EXCLUSIVE RIGHT TO SELL and in the Special Provisions paragraph state the following “This listing agreement will replace the previous listing agreement dated {date}”. Add both to loop.