Dan,
If the sending system is imbedding a 1c in the middle of the message content, it is not following the HL/7 standard for that encapsulation technique.
In my opinion, the proper resolution is for the sending system to correct their system. It may be that when they get to a certain point prior to the end of an especially long message, they mistakenly add the 1c in anticipation they are at the end.
I am not sure of the ramifications should you make the change you are suggesting. However, if you are still keen on making that change, I suggest you make a copy and place it in the site level pdls directory with a different name so no one gets confused.
Jim Kosloskey
email: jim.kosloskey@jim-kosloskey.com 30+ years Cloverleaf, 60 years IT – old fart.