Right, onto investigating a few other things. Assume your body is aligned in the X axis. You have an attachment to your right hip, which is located 2m behind you. In essence, you're doing a centaur-like avatar.
Now move along that X axis.
That attachement (a rear leg) is swinging up and down behind you like there was an invisible rod attaching it to your hip, detaching from the torso. Not what is wanted -- it's not supposed to rip itself out of the rear hip socket. It's supposed to rotate a hip socket in place.
A solution is to use joints, but you can't attach joints to yourself.
Any ideas? Or do we have to petition LL to have Little Dragon/Yowl/etc's Chakat model put in SL (and licence the Millenium Big Cat model from Daz|3d)?