it would be more intresting waht kind of yukkuri comes out if she reproduce if she is abel too do so maybe you finally find a way too cross them you could try cross them too make a nice yukkuri by mixing nice typs like yuka and chen otherhand you could make an ultimativ preadator while cross flan and alice making one who build sects serching other yukkuris too reap and kill them just for fun letting only flans alive it would be a very strong flying citysekt who could kill most of yukkuri popupaltion in shor time