Change Filename when saving by adding a digital signature

Hello!

I tried to search for this but all i find is a custom save button with script for changeing the filename.
In my case i want to add multiple signatures to a file. every time i add a signature, i am asked to save the file including the signature. i want the save option to automatically change the file name to a value like e.g. "order number" which is declare on the top.

Is there a way to implement this?