Hi Prem,
Check these 3 basic attributes which are basis to generate FI posting from CO, in your postings.
Profit center, Cost Center & Functional area,
If these do not change from the initial posting that was made from FI to Co, there will be no subsequent reverse posting, as FI considers it as no change in Financial attributes, and it really does not make any difference weather you post back to FI or No.
But i know sometimes it is hard to explain to customer, but ask you FI consultant to talk out to business why it really is not required back in FI.
Thanks in Advance.
Pankaj Bansal