PO receipt, create Lot in Lot master

I would like to understand the logic behind inserting the Lot information for the receiving branch plant in the Lot master. In intercompany transfer orders (SL/OL orders), the header branch and the detail branch are different in SL order.

If the lot number for the receiving branch plant does not already exist in Lot master, first time receiving the lot to the BP, the system creates a lot for the receiving branch plant when processing the Purchase OL order. This lot uses the same Lot dates as either the header branch or the detail branch of the SL order. We have noticed that it defaults to using the lot dates from the header branch plant (Effective, Expiry, Based on, Onhand dates). If there is no lot record in the Lot master for the header branch plant, it defaults to