Sounds lovely Jen.
I don't think that 'real interaction with other kids in a school-type setting without their parents' is an actual need for 90% of 3 and 4 year olds. I think it's just a marketing thing for all but the shyest or most socially clueless kids. I think that it also is a 'you parents can't provide all they need' thing too. So I would say, go with it for as long as everyone is having a good time let them stay with Dad. They might learn some really useful stuff, and they certianly are practicing their social interactions with Dad and with each other.
Even though I question the value of all but the best preschools in most cases, I double question the value of preschools that sort by age (almost all of them) for HG and beyond kids. Being asked to socialise with ND kids at age 3 and 4 is not a senario for building up those social skills.
One question - are you home or at work during the day. If you are working, can you shift your schedule so that you can get a morning or an afternoon a week to set up playdates during the day? I don't think that this is nescessary, but it might be 'fun.'
Best Wishes,
Grinity
