Aha so it's not a dreamfeed. Well if you can get them to see that, they might start to wonder *why* they are waking their child up to feed him. Would they like if someone did that to them? I don't think so!
Best thing might be a gradual wean, swap milk for water, don't change nappies, keep it very low key. Though if it were me, I would definitely try just leaving him to sleep and see what happens!