DamianC - Thursday, March 1, 2018 10:54 AM
I'd stick with your simple version ("IN_*.txt") on the FEL and add a script task as step 1 within your FEL to set a package-scoped variable to indicate whether to process the file (YES/NO, 1/0, TRUE/FALSE or whatever).
Use precedence constraints after the script task to control whether or not the 'current' file gets processed.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.