Sean needs onesies because he loves to play in his diaper, he is in a 3t but is in 24 month onesies, is there any place that sells 3-4t onesies

I don't know that they make 3t-4t onesies.   24 months onesies should be easy peasy to find.   

Old navy has 2t onesies:  http://oldnavy.gap.com/browse/product.do?cid=37061&vid=1&pid=612345&actFltr=true

I would say that gerber runs at least one size down---so if you by 24 months, expect it to fit 18 months, etc.   They do make 3t/4t onesies

http://www.essentialwhites.com/

http://www.dolangiftco.com/SearchResult.aspx?CategoryID=8&gclid=CM7Cr6jmiaMCFQPJsgodxA_IcQ

http://www.amazon.com/Gerber-Short-Sleeved-Onesies-White/dp/B0012J4K68/ref=sr_1_3?ie=UTF8&s=apparel&qlEnable=1&qid=1280168306&sr=1-3

Yeah I've never found them in the stores and I was sad, too, b/c I liked how they stayed tucked into pants where as the undershirts Avery went into always come untucked so skin is bare if you pick her up outside and her shirt rides up or whatever. I guess Jaret will be out of his this fall, too. I'm too cheap to order something like that, though, and pay the shipping.