Date Picker based on PO Line Item creation date

Hi all, in our P2P analysis we used to filter based on PO Header creation date (EKKO.AEDAT). However, it would be more precise to filter based on PO Line Item creation date. Looking in our SAP table for PO Line Items (EKPO), the date which is available in EKPO is always the last update date (which is not necessarily the line item creation date, in case there are changes in the PO line item after the creation). Thus, we have to also look at the CDPOS and CDHDR tables in SAP to see what kind of change have been done for the PO line item (> Insert = PO line item creation date; Update = change date after PO line item creation date). As we are not having CDPOS and CDHDR tables in our P2P data model, we are now using a date picker with the formula _CEL_P2P_ACTIVITIES.EVENTTIME. However, by doing so we would need to add component filters or an Analysis script in order to consider only the activity Create Purchase Order Item for the event time (FILTER _CEL_P2P_ACTIVITIES.ACTIVITY_EN = Create Purchase Order Item). Im looking for another way to directly have a formula in the date picker which only looks for the event time for the activity Create Purchase Order Item in order to not filter all other components / the full analysis with the activity. Any suggestions how to change the formula in the date picker in order to directly filter on PO line item creation date? Thanks Oli