I appreciate everyone's input on this, it's a lot of good information. I spent some time yesterday plating with the Girl and 3D Universe's Sara, both of which have bones for the breasts. Even when I messed around with the joint parameters, I couldn't really get any really good results. At least not what I wanted.

I spent a good couple of hours trying to make a couple of magnets into a figure, so I could add FBMs and control them like morphs. I finally succeeded (sort of) by creating magnets on a character, then saving them as a prop, along with a bucky ball primitive. I then hand coded some dials onto the ball, so you can select the ball and control both magnets at once. It doesn't work perfectly, in P5 I have to move the camera a bit after every dial change for the changes to show, but it does work. It works fine in DAZ Studio.

The cool thing is, by adjusting the mag zones, it works with any figure, and, although I haven't tested it, I would assume it would work on their clothes, too.

So far, I've only coded in two controls for two breast magnets, up/down and together/apart. I'm thinking I might add some more controls and then offer the prop as a freebie. It could be useful for making morphs, or as a good introduction to magnets, or it could just be a fun thing to play with.