Is it possible to get the *.DOC version from your online application system? If so, this matter becomes one of appending two documents together in Word, which is easy drag and drop or copy and paste. In order to convert a PDF to editable text in Word, you may loose some formatting, (paragraph indents in the wrong location or missing completely, macros removed, and other odd conversion issues) in order to bypass that if you cannot get the DOC, is to use a third-party document converter or Adobes own PDF to Doc. You can find a link to the adobe product below:
It is possible the security settings do not allow editing, in which case, simply "save as" and save the document onto your computer before opening it. (You may be opening the Internet temporary file if you hit "run" or "open" when the page began to download.)
PDF Reflow is the cause of the difference in PDF vs the Word, as above for information. (Also a list of types of text that wont convert properly just to be safe on that issue.)
So, in avoidance of that issue altogether, we can bypass that PDF security by going into Adobe, instead of "save as" this time, we are going to "print to file", to create a new document with the information you want in it. Just like normal printing, >>FILE>>PRINT. Instead of clicking OK or PRINT, you will want to change the Printer you are using to "Microsoft XPS Document Writer" and click print. Open the XPS file you just created, (not the original PDF) and again, file, "save as". This should make the PDF generated from the XPS file editable and able to accept the second page you wish to add, as well as allow you to enter the data and edit the PDF as necessary.
So PDF is not going to be a final format for you, edit in PDF and convert to Word sounds like a best option, but if the document looses part of the text during conversion, then it is likely that there are macros and other form elements that are not being carried over, and unfortunately if that is the case there is no best fix short of manually printing the PDF, after editing, scanning it back into the system using a scanner (printer/scanner) and adding it to a blank new word document as a picture (jpeg, tiff etc.)
Let me know how it goes! :)
Sorry I could not be of more assistance, if you like I can submit this for a refund for you.