End when man gets back to place second time. Anticlockwise trios arch, others pass through. You can simplify B1 by having the man walk round the woman turning them alternately. Without the reel, difficulty would only be 1. I find this dance a bit repetitive.
Trios can be any mix of sexes.
Then the RH pair make arch and LH person dances under and back home. Middle person star right with the two people on the right, turn to the two on the left and left hand star. End in place. Person on right hand end does likewise. The outside 2 couples take inside hands, and lead between the others into the middle of the room and back.