It is pretty easy to add a different drawing as a new sheet in a drawing.
Using the Merge command in the ADV DWG OPTS menu, you can merge two drawings. Merging allows increased performance and management of large drawings. Individual Pro/ENGINEER users can work in parallel and then merge their separate drawings into a single drawing file. A source file is appended to the target file as additional sheets; for example, when you merge a two-sheet source drawing into a four-sheet drawing, the target drawing then contains six sheets. You can later use SHEETS > Reorder to rearrange sheet order.
I hope this helps...