Packing Handling Units

Secnario : A delivary has 5 Handling Units.

A

B

C

D

E

I need to Create a new Outer HU (PALLET) and Pack D & E HU's into New Outer handling Unit (PALLET) F -

Please Explain Steps to do this.

How to identify inner HU 's and Outer HU's in ABAP Program. any field which specifies that ?