Well doesn't that just butter your biscuits!!! I watched Sharon Scamber's(sp) YouTube video of her shrinking a quilt block down about 1/2 inch. If I hadn't seen it, I wouldn't have believed it. She did it with repeated scratch and pressing. Watch how she does it and give the triangles a try before making a date with Jack the ripper. You could also try adding a straight of grain border along the sides. Put the triangles on the bottom and see if the feed dogs can ease them in with the correct size border?