I think this should be easier than how I do it - but maybe that is the only way...?
In the tree, expand the hole feature, find the sketch that defines the placement of the holes, click on it and select the "Edit Sketch Plane"... It is a pain to have to leave the feature to change this and then go back into it. As I type this I think it sounds pretty whiny and lame. But I already typed it, so , maybe I'll learn something - maybe not.
Shouldn't this be accessible in the Hole Property Manager? Is it? Any other way...?