all flock isn’t specifically for ducks, a duck specific feed is best (mazuri, mannapro, and purina all have them) and will keep your ducks happy and healthy their entire lives
that’s great! i recommended rehoming because that’s what most people do unfortunately. i think it’s great you aren’t buying ducks just to rehome them like most people do. personally i have 3 drakes and 2 hens, who are separated and do great. my oldest are actually turning 3 in a few months! from september until april they are all able to be together (when i’m there to supervise) with 0 fighting or mating issues