We are a concrete construction subcontractor, and find some items in Master Agreements from General Contractors unfavorable to our working agreement. Is it possible and binding to have a co-agreement in effect which outlines our terms (e.g. payment, change orders, termination of contract, etc.)? We put our terms and conditions on each of our project estimates. Is that enough to be binding if we get the estimates signed by General Contractor? I was thinking of creating our own Master Subcontractor Agreement stating our terms and getting that signed each time we are presented with a Contract from a General. In other words, putting our terms from our estimates in one Master document.