IDoc Error Processing workflow

Invoices are posted from SRM to ECC as IDocs whose message type is BBPIV. When there is an error in the IDoc input such as invalid IO and GL, invalid company code etc., these IDocs will be moved to status 51.

When IDoc is moved to status 51, work item need to be sent to approvers saying this IDoc has an error and need to be corrected. For this a workflow task needs to be developed.

In our system, there are two types of IDoc invoices sent to ECC. One is of type INVOIC01 and another is of type BBPIV01. There already exists a standard task TS00008057 which is activated for the event INPUTERROROCCURREDMM for IDOCINVOIC object type.

I shouldn't use the same event (INPUTERROROCCURREDMM) and IDoc object type(IDOCINVOIC) for BBPIV01, because responsible agents for both type of invoices are different in our company.

Please help us in getting this resolved. Also let me know if my approach is wrong towards this problem.