Trying to merge two pdf files. One file is security protected and is seeking administrator password?

[Warren32481618es89]

Trying to merge two pdf files. One file is security protected and is seeking administrator password? I have entered my password login in a few times without success. One of the pdf documents has been signed by a client via Adobe Sign that I have sent and counter signed ( in otherwords, my document). Any suggestions or where am i going wrong? Thanks!

[try67]

You can't merge a signed file with another file, as that is a form of editing, and is therefore forbidden.

You can only do it as a part of a Portfolio, which is a sort of "envelope" PDF file that has other files as attachments.