Unable to update value of PDFTextField using pdf-lib after digital signature

Question

Maybe my whole approach is wrong. I trying to simulate a signer filling a field after the pdf has been certified (digital signature). What I attempted: changing its value using SetValue, making a copy of the field and using context.assign with the same ref in hope it will create the object after the signature within the pdf structure with the same ref number. I have also tried to manipulate the widget / appearance without any success.