Family IMessages keep connecting

My family shares an iCloud. Everyone has their send and receive set to their phone.

Around once a month all our

phones get a notification saying there is a new phone - it then gives the option to add the phone to send and receive.

The “new phone” is always someone else’s in the family and it was already on the account.

Then each person has to go back in and turn the send and receive for the “new phone” off

This is very frustrating as my mom and grandma are not tech savvy and I am away at school for most of the year. Anyway to stop this issue?