Thanks lots for the quick reply, Jim.
What I was looking for is actually slightly simpler, namely to connect the last dataset in one group to the first in the next, i.e. something like this (manually drawn in the screengrab below):
I appreciate that this could be achieved by some JMP scripting as well, I was just wondering if there was an easier way to do it (ideally a checkbox "Connect means across groups").
I can achieve the same without scripting by adding another column where I combine A and B:
This works too - but again, not quite the perfect or most elegant solution!
Thanks,
Marcus