What Do I Need To Keep An Estranged Sibiling From Trying To Get Custody Of My Kids If Me/spouse Both Pass Together?

Location: Kentucky. Hello all. Basically what the title says. Background is this. Midlife is hitting and dealing with planning or mortality issues. Im 41, wife is 37. Hopefully we have many, many years left on this earth as function and cognizant people.

We dont have an answer of where we want our children to go (5 & 3) if we pass away at the same time. Both grandparent sets are upper/mid 60's, mine in less health than hers. She has no siblings.

I have two sisters from my Mom. One is... rough, to put it nicely, and I dont want how she raises her kids, for mine, and she has too much on her plate anyway. The middle sister is the basis/problem here.

The middle sister is estranged and written off. She tries to pop up every so often, but the decisions and acts of her past are unforgivable and especially for me and my Mom, we feel better off without her in our lives. She has severe mental health issues, general unstablity and recent criminal history.

I can 100% see her making a move for my kids if the Commonwealth reached out to try and prevent a foster placement. My wife worked in that field, kids slip through the cracks all the time and bad people get kids more than anyone wants to admit.

This is unacceptable for us and we'd rather foster care, its that bad. I cant stress how bad it would be. My Mom has made it very clear if her ex daughter was to show up at her funeral, she wants her barred and removed and not to know the burial site, bad. We want absolutely zero contact or involvement from her in ours/their lives.

What can we legally do, if anything, to prevent any chance she may be able to make a play on this if we both die or are unable to make decisions for ourselves. We still dont have an answer of who/where we want them to go to... we just know not her.