I'm single and childless but deeply concerned for the future of my nieces. I don't think it's too far off to think we may see a future where we return to what you're talking about here. I plan on leaving what little bit of wealth I've amassed to them and can only hope they put it to wise use after I'm gone.

If you can, you might consider talking to an attorney about a trust. I had legal insurance as a company benefit once (highly recommend it if you have an option) and it covered wills and trusts. I had legal documents drawn up outlining how money would be distributed to my minor children/their caregivers/etc. There are a lot of ways to set up funds so that their spouses can’t touch them, so if you can get in touch with a legal advisor or go down a good old fashioned internet rathole. Good luck and what a wonderful aunt you are!