Not merging a file
Accepted answer
I think your requirement is same as the existing RFE https://jazz.net/jazz/web/projects/Rational%20Team%20Concert#action=com.ibm.team.workitem.viewWorkItem&id=346757. However the RFE was closed as "Won't fix".
There's a quite old post https://jazz.net/forum/questions/36741/preventing-a-file-from-merging, which provided some workarounds for the requirement. Hope that's helpful.