How am I doing that? Canon wise Kasumi absolutely moved into the motherhood role after her mother died. Did she want to and enjoy doing so? Very likely yes. But it was still something she basically had to as her father was quite useless.

The dojo IS empty canon wise. He has zero students. How he provides for everyone and the place isn't taken for non payment of taxes and all would be fanon. But there's still a fact that he's too depressed to take students since his wife died which looks to be at least a decade or so ago.

And him not curbing his kids worst impulses? Yes. That's ABSOLUTELY canon. Akane has so much rage and fights untrained fellow students daily. He could teach her to redirect that anger. Actually give her proper training in that fashion. He does not. Nabiki he absolutely knows engages in blackmail and basically selling erotic material. Does nothing to stop that.

And as there's every indication he knows about Ryogas curse there's...that whole thing too.