When I do four patches, I sew two sets of 2 squares together so they'll nest when I'm ready to sew them together. Once they're joined to form the 4 patch, I flip to the back, remove the couple of stitches where the nested 2 patches are joined from the edge down to the seam. You can then manipulate them so all the seams swirl clockwise (our counterclockwise), then it doesn't matter how you turn them. The seams will always nest, as long as all your 4 patches swirl in the same direction. And the center will lay flat.