Multi branch index map

I have two branches of surfaces and a Proximity map of their center points. Id like to pick the 2 closest surfaces within 60in to each surface within their original branch.

On a flat list Id use that Topology output as the index map for the list item component. But it doesnt seem to like the multiple branches of the list. Any Thoughts? Thanks!

Proximity (10.3 KB)
Proximity Test.3dm (60.5 KB)

I’ve got something that I think works but it feels like more of a work around.
I shifted the list back to match the original list. Used the list item to grab them into the order. Then partitioned the list by the original lengths. Can anyone see any other ways?