Originally Posted by
Bugeyeblue But it also uses your phone number. Just thought maybe there was a way to choose to deliver only to the phone number and not the email address, which is what I think causes this problem.
No, it delivers to whatever the person is sending to. If someone sends to your Apple ID, it will show up on all your devices registered to receive iMessage with that ID.
You can set your wife to have her own iCloud account ( and thus iMessage account ) while still sharing an Apple ID for the store. That's what my wife and I do too.