"Capturing of Picker & Scanner " in Delivery document

Hi

My Client has a requirement as below. ( Its a wholesale grocery store )

1. Sales order is saved and delivery will be created at backgroun

2. Printout of the delivery docuement given to the picker to pick the items.

3. Picker picks the items and brings the items to the scanner to scan the item

4. Scanner at VL02N transaction scans the items and do PGI

How do we capture the picker & scanner details in delivery document? And pickers may vary based on material group. If i capture the details in Header partner for picker , i cant take report for the picker based on Material group. Plse help me on the above

Regards

Anis