If Snowdrop is happy without Strawberry and the trio bonding doesn't work then it might be better to bond her with Bungle and keep Strawberry on his own until you are able to get another bun and put them outside. Did Snowdrop have some health probs recently? Could they have been a result of her being upset by Strawberry's overpowering nature. If you need a temp home for one of them I can always help.