Thank you Nant for sending a new version of the cbplug_int_cbsubsremository-E file. I am glad to say that this file did solve my problem.

Initially, when I uninstalled the old plugin file (only the one file), and installed the new one, it allowed me to make the necessary changes but started giving a peculiar error during new registration.
I have the ajax check enabled for username check, and it gave the error- session expired or cookies not enabled. reload page. Even on reload, the error persisted.
I cleaned the cache in joomla and this went away.
I don't see any relation of this error with the file or its function, but thought I'd mention it just the same.

The following is only for extra information on my old problem if anyone has a similar incident:
With the default cbplug_int_cbsubsremository-E file included with CBSubs version 1.2.2 package-
1. if you have more than one group in remository, it always shows the last of the group selected in all the CBSubs plans
2. but functionally it integrates the wrong group only for the first plan in the CBSubs plans.
3. all the other plans have correct integration.

HAPPY HOLIDAYS EVERYONE AND BEST WISHES FOR A FANTASTIC NEW YEAR.