Adding Values in a Zone

I’m trying to figure out how to dynamically display the total value of items with a property within a specific zone. I know how to do it if they’re in a stack together, but stack/deck won’t work for this since the pieces need to be distinct from each other.

To clarify, let’s say the map has Zone A and Zone B on the same map window (though different boards), and all my playing pieces have a marker named “points”. Is there a way to make a text label or the like that will display the sum of “points” across all pieces in Zone A, and likewise one for Zone B (or alternatively on board A and board B, since in this case the zones correspond to boards that make up the map)?

IE I have a 5 point piece, a 6 point piece, and a 3 point piece. The 5 and 3 point are placed anywhere in Zone A, and the 6 piece is in Zone B. I’d want to put some sort of text label carrying object in Zone A that will display “8” and one in Zone B that will display “6”. Then if the 3 piece gets moved from A to B, change A’s marker to “5” and B’s marker to “9”