Hatching-Tide Quests

I'm not sure if I'm doing them wrong, or what, but it is extremely difficult to find people for these quests. Because of this, I tried to help someone with a quest that I had already completed. It seemed to work at first, since it allowed her to pick up the egg as long as I wore the right cap, we discovered that I could not see or interact with the other egg. We tried to have her turn in the egg she has and then mosey on back down to take the other one after switching hats, but the egg suddenly disappeared for her too.

Is it an absolute requirement that the person doing the Hatching-Tide quest with you has to be on the EXACT same quest as you? Or did I do this wrong somehow?

The eggs are individual. The person with you only needed to pick up and deliver theirs. I've done several of the quests multiple times and each time the other person/s only needed to deliver their eggs. I just tagged along to show them the route.

I *think* you can even leave the party as soon as they talk to the npc to start it but I haven't actually tested that theory.

You don't need to stay for the rest of the quest. Once they accept it, you can leave. On the last one with 4 people, I messed up trying to go around the Spriggans in the end. Everyone else did theirs on the first try and left. I was able to continue the quest without them, so you just need them to trigger the quest.