I agree with rlcarey; it's an amendment. You told part of the story before and now you're prepared to tell all of it. If you're not sure, call the Helpline, but you're going to have some trouble following the instructions for a "continuing" SAR.
Your second post would be the template for your opening paragraph of the amended report.
In this world you must be oh so smart or oh so pleasant. Well, for years I was smart. I recommend pleasant.