Is it or isnt it possible to sever the familial relationship after reaching majority in Missouri? i know that "adult parent divorces" was all the rage about 20 years ago, but i dont know what ever became of it, nor can I figure out how such a cause would even be drawn up.
Not that I'm aware of, but feel free to contact a local attorney.
Your best best is to create a very strongly worded will that ensures that no money goes to them and also that you have selected someone different as the children's guardian. As for the financial parts, it's easy. Set up a trust to handle your assets on behalf of the children with someone else as trustee.
I found the following description as to the process:
"With respect to custody, while either parent is alive, there is typically a preference that custody of a child be with the parent. In the event of the death of one of the parents, the other surviving parent ordinarily has a preference in law for the custody of a child. When both parents are dead, ordinarily custody is preferred to go to a blood relative, providing a grandparent with a viable opportunity to show the court that it is better for the child to be in his/her custody as opposed to other blood relatives. Courts will consider the age, health, and financial ability of the grandparent(s) to support and care for a child."
Since there are brothers and sisters who you get along well with, you could recommend that you prefer guardianship with them. List a number of choices ("guardianship rests with Jim Bob Walton. In the event he can not serve, it rests with John Boy Walton. In the event he can not serve, Mary Jane Walton....etc"). That will improve your chances of getting what you wish. Since they are blood relatives, as well, there's no obvious reason for the court to override your wishes. I believe you can also go into detail on the reasons why you've chosen as you have, but my estate attorney told me that it wasn't a good idea.
The place you might get into trouble is choosing a non-relative as guardian. I don't know if the grandparents would be able to override your wishes, but their chances would be better if you choose a non-family member, but talk to a local attorney. You need to set up a will to handle your estate, anyway.
And, of course, you may well be obsessing over something that just doesn't matter. If you're both in your 30s, unless there's some immediate health concerns, the odds of both of you dying before the children are grown is very small (unless you both participate in very risky activities together).