Bank payment status file(.txt) not in sap supported format

Hi Experts,

Client has requirement to update the payment/collection status messages automatically. we are using BCM for status updates and mulesoft for file conversions.

Bank sends us two (2) .TXT files.

first file with Collection/payment status updates for individual line items as accepted by bank , insufficient funds etc., (for EACH LINE ITEM ,NOT OVERALL file STATUS)

Second file for rejected status with different reason codes again (DIFFERENT from above reasons and again NOT OVERALL STATUS).

So with bank at a high level there is no initial acceptance file response..The response directly is for rejection or acceptance...so acceptance and rejection confirmations will come based on the value date of collections mentioned..Let's say we send 20 transaction per file (Outbound- from SAP to Bank) ,Out of which
5 has a value date of next day
15 has a value date the day after
Remaining 5 has a value date of three days after
Then response will come as the transactions are processed in different days and different files.

Can someone guide me the process to configure /map/ customize this to update the status in BNK_MONI ?

Thanks

TM