When pushing the edges, sometimes you discover things people don't know how to do yet. So if you find your own good solution please share! But here are my understanding.
Magnets can help a child connect to its parent. So if you have two independent characters, you cannot put a rope between them because the rope has to have one parent with magnets - you cannot have two magnets on the same rope.
But you can put a dragger on the end of a rope and drag it to *look* like it is connected to both. Depends the effect you are after.
What you can also do (sometimes) is have the main OBJECT-A, with a child of the Rope with a magnet to OBJECT-A, then I think you can have a child of the rope (OBJECT-B) which has a magnet to attach to the other end of the rope. That is, OBJECT-B is a child of rope, which is a child of OBJECT-A. This nesting obeys the attachment rules. This can work say if a rope is attached to a balloon (a boring object). A child (OBJECT-A) can have the rope (string) and balloon as attachments. So the balloon can be tied to the the string, then the child holds the string in their hand. I *think* that will work. It is also feasible because the ballon is pretty boring, so its fine nesting it.
Happy to kick around some ideas if you can share more about the scenario you are trying to achieve. What nesting makes sense is a key issue.