Lockbox and balance forward billing

Hi,

We have few customers who use balance forward billing and some customers who don’t. When we receive the lockbox file from bank, in the transaction number field, on  some lines  we get the BFB number and on some lines we get the Invoice number i.e One lockbox file for both BFB as well as non-BFB enabled customers. The lockbox program should identify whether the number on lockbox file is BFB or not and accordingly apply the receipt.

Please let me know what is the setup to be done to achieve the above objective.

Regards

Anand