Customizer- I would like to add a UDF to the AR ship to screens

I have been looking for the table that is linked in AR Customer maintenance/Ship to. I need to add a UDF field to the ship to screen so when the ship to codes are added and created for a customer we can add another email field we can map to Starship.

In customizer I only see the SO Ship to area. Are they one and the same and there is not one in AR?

Thank you!