I didn't finish that. Leave your new file with nothing in it except as many blank pages as you need.
Then, go to your old file, zoom out as far as you can go, and copy chunks of pages into the other
file. This will cause the new file to also import all of the styles. It should copy all of the text boxes as well
and the graphics, everything.
Then, when you have it all copied over, try adding one page at the end and see if it goes ok.
I don't know for sure that this will work, but it is a possible course of action which may work.
You will probably have to clean up the styles in the new file, because new copies will be imported with
every copy and past operation; this is why I say zoom way out, so you can copy a number of pages at a time.