You always meant to rehabilitate him and sell him. I am sorry the twins have another pony change to get used to but they do have Oscar, and who knows, another pony could come along soon! I think you should let him go.
If he stays on the same yard it might make it easier for the twins...
It would be strange if you hadn't got attached - the girls too. But I think you have to look at this as objectively as possible. Tough decision though.@squidsin I do love training them, so having a series of projects is one way of doing that.... I guess I never expected Xav to be quite so lovely! I