I have figured out a different way to do A-11 when you get to that point. It will eliminate the need for those often dreaded "Y-seams" I think outside of that, the block is pretty straightforward. I have not made it yet myself. But I have scanned the original block with my alterations to the seams This will give you a nine-patch. You simply have to construct the corners in a different manner.
Hope this helps!!
Gus