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.