Wow, Len. Do I get a prize for stumping the expert?
We were there two months ago and received child watcher passes on Tower of Terror, Rock N' Roller Coaster, and I think on BTMR at MK. I wasn't "in charge" of the Fastpasses, so I'm not totally sure. Perhaps they only give the Child Watcher passes when there's a height restriction.
We got Fastpasses for our whole group. While 1 adult stayed with our two toddlers, 1 adult and two older children went through the Fastpass line and told the CM taking the passes that we needed a Child Watcher pass. The CM gave us back at least 1 fastpass and a pass that looked like the Fastpass, but it said Child Watcher Pass on it. Then when we were done with the ride, the other adult and at least one child got to go on the ride again.
The CW pass was the same size as the Fastpass with the same kind of typeface on it. I do remember it saying at the bottom of the pass something about 3 people maximum could use the pass. I don't know if that means if there are more than 3 people you can't have one, or if up to 3 people can use it when you come back through. On at least two occassions when we used the CW pass, we received two fastpasses back so both older kids could ride twice. On RnR we only received 1 fastpass back.
I found this system much preferable to the traditional baby swap because my 3 year old has a hard enough time waiting in line for the rides he can go on. There's no way he'll wait while mom and dad go on rides without him. We were able to take DS somewhere where he could play, have a snack, etc. I was somewhat concerned that others may abuse the system, and say they falsely needed child watcher pass just so they could go through the fastpass line twice.
Let me know if you have anymore questions.