Great. I'm trying to figure out something. We're a concrete service business(Sub). We mainly estimate our projects with materials and concrete costs. However, we started a project where we only did the labor work and the contractor was responsible to pay for materials and concrete cost. However, those cost went on our account with our vendors for better pricing. The problem is that they have to invoice their investors and once they get a payment they release the checks to our vendors. However, they've paid a few outstanding invoices here and there. Now they're asking for an "unconditional waiver and release on a progress payment". Should I allow our vendors to send it out? From what I've read it seems like I shouldn't. However we've gotten paid for a portion of our work but again we only billed for labor, not the material as the agreement was that they would pay for it directly, and I'm not sure how this would apply now.