here's how you do it.....
get yourself a fastpass for EE.
(if it is just one of you riding at at time, only get one. this way if you want to grab a fastpass for something else BEFORE the time when you can get another fastpass with the ticket you used to get your EE fastpass you can. Example. you and hubby both have tickets. use your ticket to get a fastpass for EE. say the return time is in 90 min from now. make your way to another attraction that you would like to use child swap and use hubbies ticket to get a fastpass for it also.)
when the time comes for your EE fastpass, all of you, kids, hubby and you go to CM at front of fastpass line and tell them you want to swap. they will give hubby a special child swap pass that he holds. He waits with the kid (kids) while you ride. you meet up with him at an area you both specifiy. you trade off and he takes that swap pass with him and returns to CM at the entry of the fastpass line. he turns in that swap pass as a fastpass and he rides and joins up with you in that specified spot again.
DEVIATION FROM THE ABOVE PLAN:
you don't have to collect fastpasses if the attraction you want to ride does not have long standby lines. if standby is 20 min or less, we tend not to get fastpasses. that is just a personal preference though. with EE, because it is so new, i bet standby for it is going to be monster for a while.
NOTE:
if kid (s) want to ride along with you or dad or both of you....get a fastpass for them too for their first ride (in the example above - if they want to ride with you) and they do not need an additional fastpass to get right back on with dad.
also note: a place where this "2nd rider and kids must be present" thing before the CM will give you the swap pass thing is a real pain is in the land pavilion at EPCOT. You can't take strollers in the land pavilion. if you are just going in to gather fastpasses, fine, you can send in one person to get them, but if are returning at your fastpass time and hubby is planning on staying outside with the critters in the stroller - no go. you have to drag the kids out of their strollers and schlep in there with the entire group to turn in your fastpass and get your swap pass.
other than that inconvenience, child swaping is rather easy.