Question about Kids/Child Switch/Fast Passes

We have a group of 8 going on our trip in January. The kids in the group are 11, 8, and 4. I have fast passes for all the thrill rides but was curious how they handle this with kids. For example. I have a Fast Pass for Space Mountain for all 8 in the group. Obviously, the 4 year old cannot ride it. If I switch his fast pass and 1 adults to Buzz Light Year, can I still use the child switch for the adult or does that adult not qualify because he had a Buzz Light Year fast pass.

Any tips you experts have on what to do with a child while the min group goes on a thrill ride?

Thanks!

First I wouldn't say "obviously". There are 4 year old children tall enough to ride Space Mountain.

The adult and child could have a FP for Buzz and the adult could still do child switch.

Although what I'd do since everyone has a FP for Space is just have a couple adults wait with the 4 year old while the rest of the group uses their FP and then have the rest of the group stay with the 4 year old while those adults use their FP.
The wait for both groups to ride with FP won't be so long that the 4 year old would get too restless.

I disagree with the above. Why should the 4 year old have to wait for two groups and not get to go on a ride? The 4 year old is old enough to know they're missing a ride so having the other FP lets them do something "special" while the others ride Space.

What you suggested is exactly correct - get FP for Buzz for the child and an adults who will ride that or one of the nearby Fantasyland rides while everyone else gets the others for Space. You will all need to go to Space together first where they will scan the bands for the person riding the other ride with the 4 year old and up to two others (who can be people who rode in the first group) to add the swap to their bands. You can have another FP and still get the swap pass (just like how 2 others in group 1 can get the swap pass for the 2nd ride).

We did this exactly with our 4yo. DH had a FP for Space while myself and DD had one for Buzz. After getting the RS, we each rode our rides and then it was my turn on space and DH took DD on Astro Orbiter. I agree it’s not fun for the 4yo to have to wait for 2 rounds of riders.