With exnarch, it is best to consider yourself as parallel parenting rather than co-parenting. Unless you see dramatic issues that genuinely have the potential to harm them or place them in unsafe situations, normally it is best to pass it by.

Parallel parenting follows the assumption that both parents handle their time roughly the way they desire, with little to no contact existing between the parents. This is critical when the two cannot communicate or their is so much negative history that it continues to put pressure on the kids and each other.

You risk staying too enmeshed with him if you continue to
find issues with his parenting...which you always will.

Learn to distance yourself from your kids when they are with him. Tough, we know, but essential. It will also give your kids the space to navigate their new situation.

I know a woman & the father is an MD gynecologist -- no tooth brushing, hair combing, dirty clothes. He of course denies it all. I think Ns do this to bug the mother. ANd the gaslighting to deny what the mother knows to be true.

How old are these children?

Why not ask themselves for tooth brushing & sunscreen? I understand they may need help because of size (can't reach sink) & co-ordination issues (can't squeeze tube of apply well). ANd ask to have underwear when they are getting dressed. Ask their new step-mother, she won't deny them underwear. Sad but true -- children in these situations need to be proactive & their own caretakers.

I'd keep a book detailing all these weirdnesses. Also, maybe a short e-mail. "Dude. On a date, b date, c date, children came back with no underwear on. And their underwear remains at your house. Please return underwear as children need their underwear. A" See what he says. This may be something for the PC. This is costing money every week to replace underwear. So unnecessary.