Very nice, thanks @grahamgower! Two things occur to me:
Now that we don't have a shared Y axis on the figures, I think the correspondence of the nodes in (C) is less obvious. How about we keep the original IDs, and change the note to: "Note the original node IDs have been retained for clarity"?
I wonder if (A) were less wide it would be a little more obvious that it doesn't share the same X axis as the others. What if we made it 2/3 of the width of the others (say)
Looks like this: