Can AppleCare One be shared among family members devices by logging in and out?

Regarding applecare one, i understand that it’s not yet ment to be shared with the family more of one owners multiple devices.

My question or thought is, If i log in into my family members devices and then activate the applecare one then i log out and they log back in wouldn’t that work and give they’re devices applecare?

[Re-Titled by Moderator]

Original Title: Applecare Plus Loophole?