We have the same problem, but we made a Macro. This macro goes to "Search" button over the header of the windows, and the "Type" the document number to apply, and then clic on "Search" button.
If the document exist, then GP, show that document on line 1, so the macro, check "true" in the checkbox and thats all.
But the problem is when doesn´t exist that document number, becouse, GP show the "most similar number". (if doesn´t exist, GP should not allow to show any document number)
If someone knows how to modify that logic of searching, please let me know.