Hi.
As you were explaining what needed to be done, I kept thinking that it seemed like it was a disappearing pinwheel 5 block. It reminded me of this post started by sewnsewer2, which I had bookmarked.
http://www.quiltingboard.com/picture...a-t268087.html
Does this the one? If so, there is Missouri* tute for it.
https://www.youtube.com/watch?v=916sKeyxjpo