changing Apple ID

Apple ID – Create

Apple ID email address or password - What to do after you change I suggest doing this before you change your Apple ID or password.

Consider setting up Family Sharing.

Family Sharing

Family Sharing - Use your own Apple ID for Family Sharing

Family Sharing -What types of content can I share?

Family Sharing - If you don‘t see your family‘s shared content

Family Sharing - Ask to Buy

Family Sharing - purchases and payments

Family Sharing - Hide and unhide music, movies, TV shows, audiobooks, and books

Family Sharing – share iCloud Storage

Family Sharing - Share an iCloud storage plan with your family

Family Sharing and location

Use one of his devices. Sign out of your Apple ID. Then sign it back in following the "Create a new Apple ID" link. If he doesn't have an existing email address, make sure you follow the path that creates a new @icloud.com address for him (actually, I recommend this even if he does have a 3rd party email address). Then make sure you set up Messages etc on that device so that it's totally using the new Apple ID.

Now get his other device, sign out of your Apple ID, and into his new one. Make sure that his iPhone number is set up as the contact phone number for the new Apple ID, and that in Messages it doesn't have your phone number in his list.

Finally, go into Messages on your phone, and make sure that his phone number is not in your Messages list.