Ok, gotcha on D12. But I think I would tell H, "I'm backing away from the R between you and the kids. I'll do my best to let you know important events for D12, but it's now up to you to communicate with them."
And I'd let the other kids know so they know it on them if they really want their dad there. If not? He's going to learn the hard way that there are consequences lining this path. Sunny, this is no longer your job for the older kids. Yes, it's sad. But you didn't choose this for them. He did.
"There are only 2 ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle."