A new smell. Not of the pack. Intruder or welcome? Confusing signals. Alpha female smells hostile. Alpha male welcoming. Female better with pack customs. Attack intruder. Notice wrong smells. Pheromone increase in alphas. None in new female. Early reaction of alpha female due to jealousy.
Pheromone increase from both females. Mating challenge. Neither female realises. Mating challenge bad enough when admitted. Worse when denied. Second female must be accepted as part of pack for now.
Stuffed in cold box by new female. Mating challenge has stepped up. Rescued. Alpha female angry with Male. Male misses all clues. Both leave again.