I am new to quilting. Actually I haven't quilted anything yet. I have pieced two tops and am ready to get to the quilty part. I have a question however. Why does the backing have to be 4 inches larger that the top? I pieced the backin as well as the top to make this a multi versital quilt. Looks like I am going to have to use my inventivness to add another 4 inches. But I am really curious as to the why? Hope someone can help me.