In versions of Pro/E prior to 2000i, drawings sheets had to be created within the drawing.  Now PTC has given us a method of adding one drawing to another -- and it's pretty simple.

Figure 1

Just pull up the first drawing (the one you will be adding other drawing(s) to) then, from the DRAWING menu, select ADVANCED > MERGE.  These menus are shown in Figure 1.  A file selection dialog box will then appear and you can select another drawing to add to the first.  All sheets of the added drawing will be appended to the sheets of the first.

Pretty simple.

Be aware that the drawing file for the now merged in drawing still exists, so in effect, the drawing exists in 2 places -- once in the original .drw file, and again as an appendage to the now expanded drawing.

The only problems I have found with this technique have been in TABLES and BOM BALLOONS.  Filtered tables expand to full length, and BOM Balloons disappear sometimes.  Still, reworking some tables is trivial compared to rebuilding the whole drawing.