Hi Samantha,
OK, maybe trying to build the logic into the documents themselves isn't going to work. Here's a macro you can try instead. Add it to Word's 'Normal' template and it'll be available to run on any document.
Code:
Sub Mod4Pages()
With ActiveDocument
While .Range.ComputeStatistics(wdStatisticPages) Mod 4 <> 0
.Range.InsertAfter Chr(12)
Wend
End With
End Sub
Now, once your document has been generated, simply run the macro against it and however many page breaks are required will be inserted to bring the total up to a multiple of 4.