Why can’t I change family more than once
Why can’t I change apple family more than once in a year
Question marked as
Because Apple says so.
Or at least I think that's what they say, although I have hard time telling if these two things say the same thing.
https://support.apple.com/HT201088
"Remember, you can only join one family at a time, and you can only switch to a different family group once per year." June 2021
https://www.apple.com/legal/internet-services/itunes/us/terms.html
"You can only belong to one Family at a time, and may join any Family no more than twice per year. You can change the Apple ID you associate with a Family no more than once every 90 days."