Add new fields to additional data tab in customs declaration

Hello friends,

My requirement is to add Z fields in the additional data tab in transaction /SAPSLL/CL_CUS_02 of GTS. I would also like to know If its possible to create a new tab all together in /SAPSLL/CL_CUS_02 where in we can add fields from a custom table.

Thanks a lot in advance. Your help will be highly appreciated.

Regards,

Koustubh