Get user input as next dropdown choice

[Rupert]

Hi everybody. I'm getting mad to solve this out: 

I'm trying to set last user input in a dropdown selection between two choices. Let's say, after having answered the question "Where you want go?" with "Here" and "There", I need to make the user able to select in dropdwon interfaces if the route goes from "Here" to "There" or, viceversa, from "There" to "Here".

The great hitch I'm wondering how to resolve is that both "Here" and "There" are actually places (addresses) which have been just inserted manually by the user: is there any way to let Appsheet retrieve those data from the same Sheet source to which it has been just added?

Thanks a million for any answer