Make a multisig wallat, 2/2
Print out each keys, two copies each.
Key A X 2
Key B X 2
Give the copy of Key A to a group of people, family A
Give the copy of Key B to a group of people, family B
Make sure these two group, family do not know each others, but they are common known to you and close to you of course.
You can have more than 2 copies of each key but it's safer when you have lesser copies. The reason for two copies each is just in case anything happen to one copy then you always have another copy as backup.
Resembles approach used by me, except I gave them not keys but two SEEDs combined be special way ( known exclusively to me) and divided into several parts using Shamir Secret Sharing Scheme. So even in the case those three groups ( to whom those parts were handed over) somehow spot each other they will not able to access my 2-of-2 multisig wallet.