Hello Eli,
Does that mean you want to store multiple addresses not just some z-fields? You may think of creating different address types and there is an assignment block called 'Addresses' to store these values. Then you can create z-table to store these additional data for each address type and link them through address number.
We need to have a workaround since we cannot enhance the address object. Or else raise this with SAP and ask them to provide a solution.
Regards
Prasenjit