We just got back from
Disneyland where they have digital swap. So you all walk up to the podium, inform them which parent will be staying off, scan all FP's in, and then they add the swap back onto the parent who is staying behind, and 2 others in your party if you choose to do so. Yes, it's a 1 hour window from when you scan in, but if FP times are only 20 mins then you have spent 40 mins on one ride, and you are done. We just went and did other things nearby with the toddler. I went shopping, got a snack, rode something else with no wait time etc. It's not as bad as it sounds. Just budget about an hour per ride if you have a FP for it. Standby, no clue, we never had to wait in one because we got Max Pass. I would assume it's the same 1 hour window, however they cannot possibly ask that the baby wait in line, so I am going to assume you walk up and get the pass before you jump in line for standby.