If they take off their diaper, don’t give them a reaction. Calmly tell them you’re going to put their diaper back on.
“No, we can’t take your diaper off here. Let’s go to the bathroom and put it back on.”
“It’s not the time to take your diaper off. We only do that when we’re at home or in the bathroom. We’re gonna go put it back on now.”
Give them a phrase to say when they need a diaper change.
“Next time your diaper gets dirty, tell Mommy ‘wet!’ so I can help you. OK?”
“If you feel like your diaper is dirty again, you can tell me ‘go potty’ and I’ll help change you.”
Show them how to put their diaper back on to help them be independent.
“I’m gonna to teach you how to put your diaper on all by yourself, like a big boy. How does that sound?”
“See, this is where we keep the nice, new, clean diapers for when you need a change. Let me show you how we do the changing now!”
Tell them there are boundaries for touching.
“It’s OK to touch yourself down there, but only when you’re by yourself in your room, OK?”
“Putting your hand there is OK to do, but not when you’re outside or at school. You only do that when you’re alone in your room.”