I'm working on a quilt top that will grow into a 22 1/2" block. How do you square a block that big? There is a middle block of 12 1/2" which I can square and then smaller blocks around that one which have all been squared up but once I get all those together and it grows to the 22 1/2" size, I have no clue what to do. This is my first big quilt and, of course, I picked a very involved one. Thanks in advance for any help you might offer.