LOL, we'll be lucky if these questions are systematically addressed anywhere. Final answers require people having plenty of time to explore issues in smaller settings where they can feel their voices are heard. And a whole lot of research.

I think the issues need to be culturally addressed rather than legally. People are pretty inventive and the government usually makes social problems worse, not better.

You need role models to consistently demonstrate good emotional skills on the part of both sexes (looking at American history I'm not sure this ever happened on a mass scale - our history is full of families broken by alcohol, violence, and bad choices). You need adequate management of physical and mental health (problems will arise - best to plan for it and insurance only deals with the financial aspects). You need adequate caregivers (placing 100% of this role on one person is exhausting to the person). More than ever I'm certain children need way more than two responsible, caring adults in their lives and to see them with high frequency.

I don't disagree with a thing you've said, but you've basically laid out my definition of "positive role models" in a very verbose fashion. I enjoyed reading it.

Studies looking at post-birth maternal health (post-partum depression IIRC, but maybe also how the birth went) are finding that extended family structures are healthier for women than nuclear family structures. Before the mid-20th century nuclear family structures were rare in the US (and elsewhere). "The Feminine Mystique" is basically an expose of the isolating, crazy-making aspects of the nuclear family combined with suburban development and strict gender role enforcement. Prior to that mothers had significantly more support and more diverse (and challenging) contributions to the household.

In the old days, people didn't move far from home. So, you had a nuclear family (mother, father, kids) in a house that was probably adjacent to or within walking distance of other family. In addition, since old fashioned agrarian lifestyles required lots of community cooperation in many respects the kids were raised by their parents in cooperation with kin, grandparents, and other members of the community.

Much of the comparatively less fulfilling modern life and less stable nuclear family can be laid at the feet of Techno-Industrial society and innovations that have made our lives easier, but also far less fulfilling. I don't think any laws can help this situation - only dedicated lifestyle changes by people. Idle hands are the devil's playground, and people given everything on a silver platter are never happy.

https://www.victorpest.com/articles/what-humans-can-learn-from-calhouns-rodent-utopia

Don't want to go all Unabomber on you, but read his manifesto. His critique of the human misery caused by Techno-Industrial society is spot on, and has many ramifications in regards to the current problems facing families.

So that's one alternative I think deserves better exploration. And that leads me to mitigating risks. Yes, I'm largely thinking of abuse (from any of the responsible adults). My family blew itself up in pretty fantastic style, but the emotional problems were compounding well before the breakup, and seem to have been multigenerational. The breakup was the beginning of healing. So can we support families in better emotional management? Can we interrupt abusive cascading behavior? Here's an article I found that suggests we can without breaking families up: How High Point, N.C., Solved Its Domestic Violence Problem.

I'm usually not fond of solutions that rely upon state force to solve social problems. Largely because all states inevitably end up, sooner or later - corrupt. Ours is certainly well into that territory.

The other risk mitigation and family structure thought I've had is - so your interventions could not prevent family breakup? Can you recombine broken families into larger groups of unrelated adults willing to be responsible for each others' children? Does it help if you contribute to mutual finances? This is an idea I've seen women talk about, but never seen any writeup of anyone trying it out and how it's gone.

It's a thought, and you might be able to achieve it with a close circle of very good friends; but probably not. Human nature is not caring about other people's children nearly as much as you do your own. Then of course, are the systemic risks. I'm actually terrified of other people's children, and refuse to be alone with any of them. Too easy for a man these days to be accused of inappropriate behavior, and if that happens to you, the burden is on you to prove your own innocence. In the interest of protecting women and children the application of the law has gone from "Innocent Until Proven Guilty" to "Guilty until Proven Innocent" and mounting any sort of defense is incredibly costly. Our legal system is based on money, not justice. Have enough money and you can walk on murder, have none and piss off a prosecutor, you'll do hard time for jaywalking.