LIFE SCIENCES: Is their any way to enter /activate Lot Based on Date at the time of PO Receipt (P43

Scenario:  want to enter the supplier's date of manufacture at the time of PO receipt and allow the system to calculate the expiration and recertification dates for a purchased item.  Since the lot dates can be calculated using the "based on" date, it would seem a likely place to enter the supplier's date of manufacture.  However, there is no way that we can find to enter thebased on  date (other than for manufactured items).

Has anyone else run into this requirement?  How were you able to resolve it? (without customization). 

While keeping the lot onhand date is important, it should not be the basis for calculating other dates in this situation.  The work around we are doing is  manually maintaining the dates in the lot master, which is not very efficient!