I tried simply doing: $scope.arcgisId = "25", but this didn't work 😛

Property editors probably shouldn't be made to update other properties (you can do it - but it's hacky). Whats your usecase for having the value split into different properties?

The ID value is what I need to use to query nodes based on this. I have a list of id's in my front end..I n eed to use this to get all nodes which have one of these id's in this field. While the longitude / latitude values are used after the node has been loaded. Basically just need to seperate them so that one of the values can be easily queried. From what I can see, it is not very easy / efficient to query against nested object values(?)

Querying in examine? Then you can split them into extra fields there. There is a guide on how to control examine indexes here: https://dev.to/jemayn/the-problem-of-referenced-content-in-examine-indexing-umbraco-11-4355

Yes in examine. Awesome..i will have a look at this. thank you 🙂