Screenshot from the book:
These Moves come into play when you’re in trouble. When some or all of you act together (for example, everyone runs for it), the Hero in the worst position, or with the lowest relevant stat, rolls. The rest of the Heroes are assumed to succeed (perhaps with cuts and bruises) unless the Move says otherwise, or a Hero chooses not to.
My current #ApocalypseWorld game suffers a little bit from PCs always wanting to help each other, which isn't necessarily a problem
This MC move is basically a prompt for them to describe their narrative positioning, which will make it obvious who can help and how