How do I re-sync accidentally deleted messages on my iPhone from my iMac?

richardesigner wrote:

If I restore a backup won't it get rid of all the messages I have sent/received from now back to a month ago?

Yes it will.

So it sounds like your iMac will be the platform of record for these messages.

The only way i can think is to go to your iCloud at the top of the settings page (Where your name is) Press on it, then select iCloud and where it says messages switch the switch to "off" You will then see a box that pops up and says "Disable and download messages" Press that and then once that box goes switch the iCloud switch button back on. Make sure your iPhone is connected to Wi-Fi an power and when opening the iMessage app it should display a message at the bottom saying "Downloading messages from iCloud"

This is all dependant on if your messages with your Wife are still in iCloud.

Hope this helps, if you run into any problems let me know. Stay Safe, Sean.

Just to be sure we understand each other, here’s a quick semantics point.

richardesigner wrote:

Yes. My messages are backed up to my iMac.

I worry about saying the messages are “backed up”. There is a separate instance of those messages on your iMac. They’re really not “backed up” in the sense they can be restored to the iPhone. They have a separate life on your iMac.

Messages do not sync. Instead they are captured on your latest iPhone backup. Restore that backup to retrieve the messages that were present when the backup was created.

Go onto your iMac, open messages, select messages from the menu bar at the top, select preferences, and then the "@" button and make sure "Messages in cloud" is tuned on.

Just to be clear, since you house your messages in iCloud, they are not backed up anywhere.

Once a message is deleted from iCloud, it’s gone.

Glad that helped.

Enjoy your Apple gear.