Hi ALW,
For showing google map you need to have an address field which will store address that you want to show on the map. In your case, is 'Add another' attribute an address field which will have the address of a location you want to show on map? This is what we have understood. Please let us know if we are on the same page.
We have successfully implemented this feature in one of our projects and it is working fine. Please let us know.