I think it would be foolish to automatically assume that the 12 year old is better than the 2 year old. Don't get me wrong, I think that an inexperienced family needs an experienced horse. I have met plenty of horses over 10 though that are fruit loops. You'd be better off to sell your baby than to trade if for something worse! The trade may be a good one, but make sure that it is before you complete the trade. Make sure it is very calm and get the vet check. Do some reading first and ask lots of questions.