How to allow only add content (No modification to existing content) and printing in a pdf

Hi, I have disabled all the properties of pdf using code in C#. Now the user wants to add content to the pdfs ,but they should not be allowed to modify anything.
Basically, only below actions should be allowed :-

  1. Printing
  2. Adding new content

However they should not be allowed to modify anything in the pdf.

If anyone could provide any help on this i would be highly obliged.
Thanks.

@Ajay.cfins

Have you tried generating a PDF with similar restrictions using Adobe Reader? Please share a sample PDF in which only these permissions are granted, we will try to create similar output in our environment and share our feedback with you.