Hi RG,
As you having multiple batches of same product with same manufacturing dates then why the operator need to pick one HU which is behind other front HU's. He should be free to pick up the front HU's first and then he can pick other HU's as n when required. It should not cause any issues or harms for picking.
I am not clear exactly what is your requirement, if possible can you elaborate more about your requirement.
Regards
Anoop
