Good news! Invest in several (3-5) fitted sheets. We have some from when I trained Mark (and then Mariella). My in-laws swore by their method, which was to take their kids and hold them over the toilet about four hours after they'd gone to sleep. They claimed their sons stayed asleep while peeing on the toilet.

I never tried that. I did used to go in about 30 minutes before Mark would wake up and bodily lift him to the toilet (or onto the potty). I didn't do that with Mariella. Best of luck. I've changed sheets three times during a night for a couple of nights. Sleep? What's that?