Adding Notes to Emails

Part of our workflow is currently editing the body of emails we receive(usually invoices) to provide context for the invoice and provide general information about the invoice. But I am having issues with sync and apparently this feature is getting removed in the new outlook anyway.

I have tried making custom forms but I can't figure out how to apply them to emails that I receive. Is there anything I can do short of sending them to a group one note?

Ideally we can keep this whole workflow within outlook.