Hi,to explain why you cannot combine the XFA PDF with others:Assembling
PDFs only works with the same "type" of PDF.The most common form of PDFs
is what I call the Print-PDF. That is what the majority of PDFs out
there are.Then there are special variants such as XFA PDFs. These need a
plug-in in Adobe Reader or Acrobat to render them in their final form
while being opened.Because these two are so different, it is not
possible to combine them in Acrobat.You can "flatten" your XFA PDF (it
will not...