Hi Ravi,
When i did the provisional/final posting implementation so as to pass the Foreign exchange exposure back to the subsidiary where the original payments were raised, the posting into FX account from FEBAN was performed manually by local treasury users so did not automate this.
Reflecting on how you could automatically post FX by FINSTA bank statement from IHC, I would be looking at using GL tolerance group only specifically assigned to IHC outgoing clearing accounts posted by F110 with large margin of payment difference. Unfortunately the account determination GL difference posting (t-code OBXZ) is not by tolerance Key level, if you are already using such functionality and need to post into different FX gain/loss account, you might need to look at BTE/User exit/substitution route, while if you are not using GL difference posting, it would be simply to assign FX gain/loss account for this to reflect the difference between the local currency translated at M rate and market rate by banks.
hope that this helps
Kind regards
Taro