1) In attribute manager select any city and append it from the left to the right column.
2) In the right column, now use append to recopy that city back to the left hand column.
3) You will find a new city (2) at the bottom of the list,in my example Boston(2).
4) Below the bottom of the left hand column you can now edit this copied city as any name and coordinates you want.
Of course apply and save everything, then save as an .AAT file for safe keeping.