Help - I need to insert a pdf file into my output

I have a project that requires some pages of regular variable data stuff followed by a page and I guess an overflow page that will add another pdf file in at the end of the other pages. The pdf file to be added is indicated in one of the data fields. The pdf files to be added are all different page counts.

What I need help with is how to set up the template page and overflow page so it will insert the selected pdf file into the final document.

I have searched inserting PDF and a few other words to try to see if this has been discussed but I have not found anything.

Thank you.