It just happened that the escape plan that Lewis and Alexander came up with had something to do with falling off of the ship - something like a blindfold test that challenges their trust.
Lillian received a message from the fairies that instruct her to escape by jumping over, and letting the fairies that are waiting for them below to catch them. It turned out that the fairies she talked with earlier had their other friends already positioned at the bottom side of the deck - all prepared to catch them once they fall.
And that's just what took place.
As soon as Lillian pushed Felicity to this unbarricaded part of the deck, she ends up screaming on top of her lungs and catching everyone's attention. Even then, she just continues to shove her all the way out of the ship then into the ocean.
