Joyboy likely ruled the Ancient Kingdom, if Lily sided with the 20 then she knew they were gonna fight Joyboy. It would be better if Oda goes with a breakdown of relations between Imu and Lily that lead to her refusing to join the others in Mariejois.
Yes, she probably got un-alived by Imu and then Imu took her sword to the garden.
Yes, she probably got un-alived by Imu and then Imu took her sword to the garden.
so the 20 kings joined forces to stop 'evil joyboy' and won - only for lily to soon realize they had all been duped and everything imu told her was a lie. she then 'disappeared'.