IIRC he wrote it right after Douglas Niles wrote the first moonshae novel, which actually got printed before the original campaign module, back in '85, followed by Crystal Shard in '86. Of course Greenwood was working on the setting since the 60s, so he probably had a complete list, but authors had a lot a free reign and canon didn't exist, which is why, if you read many of the early Harper books, things are a portrayed very differently from book to book. Lots of stuff that pops up gets carefully stuffed away too. Officially Windstrom is a demigod of the other, in all likelihood RAS got a note from Greenwood or one of the others telling him there alreayd was a ranger god.