Saving PDF form to flat pdf document / merging completed form with JPG

 
I've been struggling for a while here trying to be 'efficient' and running into issues with getting Acrobat to do what I want.
 
I'm trying to prepare document package for faxing without printing hard copies. I had hoped to do it all by joining, two pdfs docs, and a PFD form that my secretary fills out. The challenge is that two pages of the form are signed in paper copy and sent to me as JPG.
  
I need to take the PDF complete form, export just the first 4 pages as PDF document, then merge it with two other PDF documents.
  
When I try printing the completed form as a pdf is doesn't all it and suggest I use Save As but seems no save as options create a flat file that would allow me to delete pages are replace then with the JPEG scans.
 
I'm not a programmer.... but generally pretty clever I though. Using acrobat Pro on a macbook. Thanks for any advice!