Meliantha's sword makes her immune to all forms of mind control as long as it's within 30 yards of her. There's been a bunch of times I've had her with out it, just to balance that out (they'd freak in the hospital, for example, and at parties). It also is in constant psychic contact with her, so the first one may have a counter in that even if Chainbreaker isn't right there, but it's not a perfect one.