Recover text messages deleted from phone but still on Mac?

I just accidentally deleted my entire text thread with my dad from the last 8-9 years. It's still on my Mac in iMessages. Is there any way to merge the two?

I do not want to do a backup restore. It's been awhile since I synced my phone, and I also do not use iCloud. My carrier is Verizon. What are my options?

I read that you can turn off and then turn on iMessages on the iPhone and it'll merge the two, but I'm absolutely terrified of losing the thread even from my Mac. I only read this on one site and it was an old article, so I'm skeptical until I hear more confirmation.

Thank you incredibly much in advance!

Note to self- do not use phone when woken up after just two hours of sleep. That definitely woke me up...