Mark a PV de réception as manually signed to release the balance

I want to be able to mark a PV de réception (completion certificate) as "already signed" manually, similar to how it works for quotes. Currently, the "Demander le solde" (request balance) button is blocked until a digital signature is performed on the platform. Many of my clients sign paper versions or struggle with the digital signature, and I need to be able to upload the manual PV and proceed to the final payment request without being blocked by the system.