Where to input Quantities Produced so an Contract Billing invoice picks up these QTIES to bill out.

E1 9.2 Contract Billing

TR = 9.2.4.3

Hello

We currently input our Quantities produced via the P510171 ( QTY ENTRY - REV) .

We then create an contract billing invoice via ( R52121) and these REV QTITIES come into contract billing and we get an invoice created for the QTIES produced.( automatically)

We are running into issues where at the initial time of inputting these QTITIES , there is incorrect data and this incorrect data flows down into the Contract Billing world and is never recognized as issues until it is to late and the invoice is sent out to the customer .

Is there any other way/processes to get QTITIES produced invoiced out thru contract billing billing besides using the P510171 and or doing the manually update via the P52221.