[QUOTE=madamekelly;7375591] As you sew them the edge that does not stretch will be against other edges that do not stretch, and the stretchy edges will be sewed to each other.
I try to do just the opposite. I try to sew a not stretchy edge to a stretchy edge. That way, everything is more stable. I was given a box of large triangles cut off the corners of fitted bed sheets. They were waste to the factory that sold the sheets. I sewed them together straight edge to bias edge and made about a dozen pillowcases. If there were bias sewn to bias, that seam would sure open when the bias was stretched.