Hmm, for new "Project Assessment" records, i.e. ones created by your automation, you've already set it up so that the link happens automatically, so I assume you're talking about existing data?
If so, this would really depend on how your data's set up and whether there's any pattern you can use to identify which project assessment records are associated with each project. You'd use that pattern to either create an automation to do it for you or you'd have to do it manually I'm afraid
