Happy to see that the issue with the map has now been resolved. If I was programming this, I'd have an array/collection of processed Location IDs while looping through them. On each Location I'd check the collection and skip the Location if its ID was already in the collection. I don't have enough Toolset experience to understand if something like that is possible.
We are limited in what we can do with the Toolset UI to achieve the above scenario. It would be as simple as you describe it with a few lines of code but since you're working without applying any custom code then to identify some uniqueness in the relationship isn't possible.
As for your last suggestion, to only display 1 item: I don't fully understand the approach yet, but what I can say is that in this scenario we do have only 1 Location per Town.
I was mentioning here that you can have your view list out only 1 item because there is a limit and offset setting on your view that will allow you view to display only 1 item in the loop. This means that if the post has 5 parents/children then the view will only display 1 item instead of the 5 because there is a limit setting being applied to the view.
If you say only one location has this checked then maybe you can apply the code in the view that is displaying the location.
[wpv-conditional if=" '[types field='main-town-location' output='raw'][/types]' eq '1' "]
I looked into this again based on your latest suggestion, but finally decided to take a different approach due to the complexity and time constraints. I removed the map, and instead I added two child views in each loop item to display additional information that would otherwise be in the map. The map will be missing but from a user perspective the view is still good enough.
