I could have file numbered each frame but that would have made it look as if I was soliciting orders.
Isn't that the name of the game?
A couple of ideas.
Use print to file for each the pages and re-print fitted onto A4 pages.
Or
Print to a pdf with the A3 paper size.
Reprint the A3 pdf to a new pdf with A4 paper & fit to margins set.
The advantage of a pdf is that you can e-mail it and the recipient can easily open and print it.
I use Tracker software PDF Xchange Lite which is free to non-commercial users, you'd have to pay. However PDF Creator is free to anyone as it's Open Source.
It would be much easier to give the images on the A3 page a reference number
Terry