getting the amount of parts between two parts using getconnectedparts()?

Im making a physics system that changes part stability when they are further from a stable part. while doing this I tried using magnitude, this failed because if a part is near a stable part but not touching it will become stable itself.

back to my question I want to get the parts that are in between two other parts using getconnectedparts. is there any way to do this? I know getconnected parts can either get the adjecent parts or all the connected parts.