[LunarBerry]

My baby-girl Kimchi, has only learned recently that she can open a door "further" if it's cracked ^^; I'd try having them sit in front of it and let them see it can be opened by maybe having their paws on it, or showing it can be opened or, if there's no other dogs, have a decent sized toy that's tied to a string/rope and pulled through it so they can see it's possible to go through it. Just a thought anyways. lol we have older dogs and she follows by example at times.