BAPI for update Purchasing schedule agreement delivery schedule in 4.7

I am looking for a BAPI or function module to update a delivery schedule for a Purchasing schedule agreement. I have seen in the threads a suggestion to use BAPI_CONTRACT_CHANGE. However we are on 4.7 and that BAPI does not exist. I have tried to use BAPI_PO_CHANGE but it gets an error saying it can not be used for scheduling agreements. Also BAPI_AGREEMENT_MAINTAIN only updates the headers and line items, not the delivery schedule.

Any suggestions on how to do this in 4.7?