M.
I know what I am going to say may be painful, but others I know had to set their alarm to wake at night, go in and bring their child to the bathroom. For example, they would put their child down at 8pm and go in at midnight or 1am and bring them to the bathroom. This one middle of the night trip to the bathroom kept them from being wet in the morning. Eventually, they will wake at whatever time they need to and go themselves. My daughter didn't need this, but many mothers of boys specifically had to do this method.