I have taken a piece of stabilizer and ironed onto each block.

I don't know if you used Steam to Press your blocks, but, for me, steam distorts all my fabric and makes a mess of those wonderful straight edges I started with. They do look wonderfully flat, but what good is flat if they wave on the edges and the squares are no long square?

I do not use starch. I just try to handle the bias edges the least amount possible and I will run a staystitch 1/8" inside the edge of a long bias edge if the edges try to distort. Make sure the piece lays flat. If the piece cups up, then your stitches were too short or tight. Short bias edges don't really need the staystitch. Of course, this isn't going to help you after you have already stretched them.

When I have eased in fabric while sewing a garment, I have run a row of long running stitches and pulled the bobbin thread to make the piece shorter to ease it in. The extra fabric is eased in over several inches, not in just one clump. After the quilting is done, you won't ever see that tiny bit of excess.

I steam my fabric and iron it in every direction before cutting. It can't distort anymore. Works great for small pieces.

Tartan, of course, is right on -- and I taught college level sewing classes for many years.

I starch the snot out of it before I cut any of it. That will usually prevent about 98% of the problem. When that bratty little 2% shows up, I can often steam it into behaving itself but I only hover over the fabric and steam it. That relaxes the fibers and encourages them to return to their original state.

I'm in the starch, starch, starch and more starch camp. I did a quilt top last year that was all triangles. I starched the fabric until it was like paper and had no problems at all with the bias.

I agree that starching your fabric will help it hold a lot.

I don't use starch. I use pins to hold edges together and remove after stitching. I am careful not to stretch.