Rider swap / baby switch. New rules?

[Charlie30]

Hi!
I understand that there have been some changes to the child swap process recently.
We are 2 adults and 3 children.
Last year, 1 adult and 2 children fastpassed a ride, then the other adult plus the same 2 children would then ride again with the switch ticket.(a physical ticket from the cast member)
I believe that the switch is now added to magic bands?
Is it an open return for that day or do we have to switch immediately for that ride?
Also, is the rider switch that is added to the magic band an extra open fastpass for effectively any ride or does it specify that exact ride on the MDE app?
Just thinking out loud as to whether I could get the rider switch for say slinky when the rest of them ride as my son will almost certainly not ride but walk him over to TSM instead? (Forgoing my ride on slinky as a swap and using his sisters magic band with the rider switch pass on) In the same tier of ride.
Does this make sense?
Thanks all!