It would work the way it does now. No. 9 would arrive back at Sheepscot, and No. 10 would couple to the north end of the train. When No. 10 has cleared out, No. 9 would receive service and take on water, then await No. 10's return. No. 10 would cut away at the south end, and No. 9 would couple to the north end, ready to go. When it has cleared, No. 10 would receive service and take water. Etc., etc., etc.