Can you teach a dog to poo on command?
It would be great if you could but I have never met anyone that has managed it. However if your dogs are fed at approximately the same time each day and you know approximately when they usually poo you could make an effort to take them out of the run at around this time. That will probably be the closest you’ll get to getting them to poo on command, for the basic fact that its a normal bodily function that you cannot force (if you can’t poo on demand then I’m guessing your dog can’t!) but at the same time taking them out of the run should teach them that you do not want them pooing in there because you will be taking them out of it to go to the loo.