I am sure this problem has been addressed in some application but I don't know where to look. Here is what I want it for. I designed and created a two point swivel for my "dog run". I have two huskie and did not want to fence in a large outdoor kennel. I put in an overhead cable running about 100' from the house to a tree, placed a trolley on the cable, a swivel on the bottom of the trolley and a bracket holding two 25' retractable cable leashes in the bracket. They can run and play without getting tangled. See photo.
The challenge! I now have three huskies. Somehow I need to attach three of the retractable leashes such that they can't get wrapped around each other. Any ideas?