But the problem with the parallel rules, AR's, and various memos - it is complicated.
But in summary given those rules, AR's, and the current memo item #10 we end up with something like:
1. If the extra B departing player(s) who have been on the field for more than three seconds
2. are clearly near the sideline and heading off of the field without participating in any way,
3. and have
a. not been in a defensive huddle,
b. and have not in our judgment been in a "formation",
c. or have not in our judgment intentionally stayed on the field to mask the defensive alignment
4. and the departing player(s) is/are still on the field at the snap
we would then have a live ball foul, otherwise we have a dead ball foul?