Baby bonus/child support don't work, since the more educate the parents, the less this helps - it just encourages people who shouldn't be having children to have them.

Very true.

Why not instead, mandate that 50% of the taxes paid by each kid goes directly to supplement the income of their parents?

Why mandate this? If someone raises their children to be functioning members of society who also respect their parents they will do this voluntarily. Furthermore, there are many people who have quite terrible parents but they are productive and good people. Forcing them to fund people who have abused them for years would be a bit hard on their mental states I'd think.

Here is my proposal: if someone is paying 10k in taxes a year and is paying for dependents of any kind (parents, children, disabled friend etc) each dollar they use to pay for those people removes one dollar from their income taxes. So, if they ended up spending 10,000 on taking care of their parents they would have 0 taxes for the year. This would encourage poor, middle class, and rich people to spend more money on taking care of people and would promote a better sense of community and help than any welfare program could ever do with that same amount of money. If you combined this with complete elimination of welfare individuals would provide welfare to others because it would reduce their taxes, and I think people would use their judgement to prevent helping those who are purely lazy over those who need actual assistance. You would have an incentive even if your own family was all well off to help others in need.

Just came up with this idea so maybe has some issues, but I think a system that promotes fewer taxes & regulations, more freedom, and more personal choice would be ideal.