Hi Jack
BCM bank communication managment module only works with PMW, and not with IDOCs using RFFOEDI1. That is the reason why IHC payment does not appear in BNK_MONI
BCN is meant to manage the interconnection between SAP and external banks so i do not see much point in havving BCM batches created for Internal payment from subsidiaries to IHC.
As regards the payment run ID between internal and BCM, could you not implement user exit/BTE to validate against the payment method?
Hope that this helps.
Kind regards
taro