Before i will show you some Code, first try to do, what i described and try to understand.Find out similarity to your project.
I saw that you have tried to setup the DB-Preset in the example but it did not work for you right?
So i have done the SETUP by myself. Now you are able to use the example and see what is possible.
Once again, with this integrated form here. . .
https://www.media-junkie.com/locations
…you can add new locations to the shown database in DB-Preset-3.