D..
Don't get tougher. It will backfire on you.
First, let me talk about the morning and wet diapers. Night training is a different thing than day training. You should not be trying to do night training until after he is fully day trained. Plus, he may not be able to night train for a good amount of time. The brain and the bladder have to work together to do this, M.. My ped told me that many kids aren't physically able to do it until after they are 4 years old. So leave his diapers on and don't talk about him being wet when he wakes up. Focus only on day training.
When your older son needs to go to the potty, ask him to ask his brother to go with him to the potty. Is your older son sitting down or standing up? Ask him to sit on the potty instead of standing. After he finishes, then have him ask your little one to go too.
Try for every hour. Don't ask him if he needs to go. He doesn't know if he needs to go yet. Happily say it's time to go to the potty to both of your kids. It's good to do it when you are transitioning to a different activity rather than in the middle of him playing with something.
Don't do anything else at this point. Backing off your night time expectations will help. As he gets used to going to the bathroom, he will gradually figure out what a full bladder feels like. You CANNOT make him feel this, M.. His brain has to "get it". No amount of "toughness" is going to make that happen. And if you get tough, you can upset him to the point that he simply won't go.
Remember, don't even attempt night time training until he is day trained.
Dawn