A friend got a new phone number. I merged that with her old contact, keeping her old number. That combined the old thread from her old number with the new thread from her new number. When I started using iMessage on my MacBook to text her, the two separated again, both on my MacBook and iPhone. Is there any way to keep the two threads merged in all three formats (iOS, macOS, and iPadOS)?
MacBook Pro
Hi there, gman91478.
I see that you're having a problem when sending iMessages to a contact from your Mac. You added their new number to their old contact card and the messages on your iPhone stayed together. Now, they've been separated on your iPhone and Mac, and I'm glad to help.
About iMessage and SMS/MMS -- If they've separated, have a look at the color of the text bubbles in each. If you're seeing one thread has blue text bubbles, and the other is green, one is being sent by iMessage and the other is sent as SMS/MMS.
How to forward SMS/MMS text messages from your iPhone to your iPad, iPod touch or Mac -- Since you need a text message plan in order to send and SMS/MMS message you can use Text Message Forwarding between your iPhone and other devices. I'm not sure if this will merge your current threads together again, but it should moving forward.
Keep all your messages in iCloud -- You can also use iCloud to sync your messages between all of your devices.
Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch -- This article explains all of the other features of Continuity.
Take care.
Merge iMessage threads from same contact (iOS 13 and macOS Cantina)
