To get to the proper ending position, it is always possible to do the call in
each group of 4, and then those who end as the centermost 4 dancers
do a 'Substitute' with each other, moving away from the
dancers with whom they have done the call. To dance this smoothly, the
substitution is accomplished at some time during the call.
This optimal time (usually toward call completion) varies and is dependent upon
the call. EN: 20