iOS 12 texts messages to my wife not showing on her phone.

If you can't send or receive messages on your iPhone, iPad, or iPod touch - Apple Support

I talked with apple support for nearly an hour and was told the only way to troubleshoot a similar problem was to start deleting threads on all devices. When daughter 1 sends a message to mom, it doesn't always come through. Sometimes it comes on my phone (dad), and when I reply to daughter 1, it changes on her phone from sent to mom to sent to/from dad. Daughter 1 can text daughter 2 and vice versa, but it mixes me and mom up. Same issue with airdropping photos. With Apple being such a big tech company, they should have delayed this release of iOS 12 or already have a resolution.

Everyone needs to be on their own Apple ID.