Hello mate,
I understand that the original component is a standard component. all you need to do is,
You find out the view in which you need to have the additional field.
Now,
go to transaction bsb_wd_cmpwb
enter the component(GS_CM in your case)
you will have all the views.
Right click on the target view where you want to add the custom field.
Say 'Enhance'
Now provide the transport request and enter.
Go to the relevent context node.
Right click and add attribute.
End the wizard process after selecting the correct attribute.
Activate.
Then go to the configuration.
select the configuration and edit.
You will see you Z field in the available fields.
Add that field to the config.
Activate.
Please award points if this was helpful.
Cheers!
Partha