From a generalized 1/4 tag (usually a right-handed 3/4 tag): centers
Trade and Roll and then walk forward, passing right shoulders, to become
#1 and #2 of a column. Ends Divide, Touch, and do a sort of Flip the Line 1/2
to become #3 and #4 of that column. All passes are right shoulder, even if
the starting formation makes that awkward.