migo tcode enhancement problem

Hi all,

There is a requirement in MIGO tcode where if movement type 101 and the doc. is of purchase order then there is a tab at header level for transport where i need to mandatory few field?

How would i proceed with this problem? I have few details of that MIGO tcode

Program for subscreen where transport tab is there is SAPLZMIGO_BADI

Program (Screen) : SAPLMIGO

Program (Subscreen ) : SAPLZMIGO_BADI.

Please guide me.

Thanks

Parag