While I don't know how a Summoner's Egi deal with the jumping between islands mechanic when fighting Kraken, I noticed that Eos and Selene will continue to follow me as I jump between the islands, in spite of the fact that I command them to stay in one place with the Place/Stay commands.

It would be very helpful if I could command my fairy to stay with the group, keeping her in healing range of the rest of the party, while I jump to another island while handling the World's End mechanic.