We are trying to collect payment - there are 2 invoices. They are saying they will not send us one of the payments without signing the waiver. I do not want to do that, because what if they decide not to send the 2nd payment? I have not signed something saying I cannot file a lien. They claim they were supposed to have us sign that waiver before we even started work, but they forgot. Now, 3 months after the work is complete they are trying to get us to sign it and say they will not release payment unless we sign - can they legally do that?