auto adding or merging under program ocntrol

WITH PDFCREATOR IT SEEMS QUITE EASY TO PASS THE FILE NAME WANTED TO THE PROGRAM. BUT! IS THERE ANYWAY TO SEND THE REQUEST TO ADD ON TO AN EXISTING FILE, INSTEAD OF CREATING A NEW ONE, AND THEN MERGING THEM. 

SOMETHING LIKE A "+" PLUS SIGN OR SOMETHING IN THE FIRST PSOTION OF THE NAME TO SHOW THAT WE WANT TO ADD TO THIS IF IF IT EXSITS.

DOES ANYONE AHVE ANY SUGGESTIONS?

THANKS