that happens to my iPhone, my 2 kids, iPad and macbook pro
heres what you do
Settings> Messages> Send and receive>
then for you your number will not be highlighted but your wifes will so just click on it and make sure the check mark isn't next to it and then on the bottom it says start new conversations from and make sure your number has the checkmark
** if you use FaceTime make sure the email isn't checked (if it is then when they FaceTime to your email all your devices that have FaceTime app will ring)
i have to do this every time we update
we each have our own iCloud email but for the apple id we use the same email, it keeps us linked yet our backups are separate
hope this helps