I am a subcontractor who has completed 5 projects for a GC. He has paid the contracted amount on the 4 previous jobs, but on the 5th he is claiming we overcharged on that and 4 previous jobs and is subtracting the amount from the final payment of the 5th job. We signed Release of Lien for the previous jobs, but if he is retroactively taking back that money then those would no longer be valid correct? We have not paid for the material on 3 of the jobs and there have been additional cost incurred that we have sent invoices for but have not been paid on. The supplier pre-liened, but we did not as we didn't sign up for this service until recently and hadn't had any issues (didn't know any better). I wan to allow the supply company to collect the money owed them by liening the owner. That way our material account is cleared and in a way we have collected our money. We are in MN and one of the jobs was here. The other 2 were in WI and IL respectively. Any issues with this plan?