Hi Rahul
In BadI CUSTOMER_ADD_DATA, the button 'Transportation data' make reference to a screen group, when you implement this BadI in method CHECK_ADD_ON_ACTIVE you can activate o deactivate the screen group. This make the button appear or disappear, but this is made before enter the customer.
In your case, in method READ_ADD_ON_DATA you have to access the memory to get the table GT_SCGR_ACTIVE.
Assign (SAPMF02D)GT_SCGR_ACTIVE to a file-symbol, then you can activate your sceen group.
Regards.
JCD