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I do also having the same query about my site https://www.uaeadvise.com/ please if anyone help me with this. Thanks in Advance!!

Hi Fraser! Is the new website based off of a third level domain or within a certain folder of the domain?  If the domain has remained unchanged from new to old the old campaign should be working with both the data from the old site as well as the new.  Cross check to make sure that is the case then you can likely delete the new campaign without any ill effects. If that's not an option you can always aggregate the data via CSV and present it in your own format. I'm unaware of a way to combine campaigns. Cheers!

We've also seen some drops across our website and our competitors domain authorities. Glad its not just our market.