I can imagine Grace getting caught up in it and then feeling guilty, as she did with Franky. But what seems more plausible is that she was mates with Liv and somehow they ended up mates with Mini so they continue the bond in order to stop themselves being targetted.

I doubt that their group will last long though, and Mini isn't going to like it when the pair of them start to build their own lives without her. The stuff at the shopping centre was just a taster, and look how badly she reacted to it.