Friend’s new number won’t sync with iMessage conversation thread

My friend got a new number but messages won’t sync our iMessage conversation thread. I now have 2 conversations listed on my message app and it’s super annoying. I made sure to delete the old number so that’s not the issue. There also seems to be an issue updating the contact (which I assume is related) when I go into the message she sent me from her new number my phone makes a “suggestion” to update the contact card and so I do and “add to existing contact” but now I have the same number listed 7 times in one contact!!!

This whole iMessage conversation thread issue has now happened to me multiple times where I have multiple conversation threads with the same person even if I have all their info in one card (ie their number and iCloud account, Apple ID etc)

I have tried what feels like everything and am frustrated hope someone can help me out! Feels like it should not be this complicated