These work with both Legacy RefWorks and ProQuest RefWorks and upgrading will not change which Add-in you use.
If you have used an Add-in with a document and Legacy RefWorks, you will be prompted to update the document to match your new ProQuest RefWorks account the first time you use the Add-in with your document and your new account.
Make a back up of your document.
Open the document and Add-in.
Make sure that you are logged into your ProQuest RefWorks account in the Add-in.
Follow the onscreen instructions to update your document.