Update PDF with existing Signature

When using Merger to add an annotation to an existing PDF document that includes a digital signature it seems to remove the original signature.   Is there a way to do this while preserving any pre-existing digital signatures?

Hello,

Presence of a digital signature on a PDF indicates that no modifications were made to the PDF after the author signed it. After that point, any changes to the digitally signed PDF is supposed to invalidate the signature and this is expected behavior. If you have the signature file, you can re-sign the PDF with Merger after adding annotations. Please refer to the documentation on digital signing here.
 
Thanks,
ceTe Software Support Team.