as whats already been said, this is the reason you should break a pup on its own, its stops the jealousy and bad habits,
yes they can learn quicker from an older dog but if its in them it'll come out, just takes a bit longer
but you should be stopping the dog doing what its doing, you've allowed it to become dominant over its catch
dont allow another dog to put it in its place, it could be a recipe for dissaster