Hi,
I suggest to use a TVARVC variable in combination with a small ABAP program. On the selection screen of the program you can select the ConpanyID1 you want to process. The program will update the TVARVC variable. This program you should run prior to execution of the Process Chain.
In the InfoPackage you can select a file from the application server. Here you can specify a routine to determine the file path/name. Here you could prepare the appropriate file path/name by evaluating the value of the TVARVC variable.
It could be a powerful combination with Logical File Names (t/code FILE). You can use Function Module FILE_GET_NAME_USING_PATH for this purpose. Please refer to the documentation of the Function Module for an example.
Best regards,
Sander