Child Swap and FP+

[CaryHaven]

If our daughter is too small to ride with us, do DH and I both need FP+ for a certain ride to use child swap, or only one of us needs a FP, or is it only standby that this is even needed? I'm a little confused and can't remember how we did this before.

EDITED TO ADD: nevermind - just saw there was another question on this already