When suggesting the quilting being done be more circular, why don't you take in some see through paper or plastic & a marking pen & show what you are talking about. A lot of people have to see it to understand it. I would suggest, if you are using a clear piece of plastic, either sew or glue an outside border (could be duct tape) on it do you don't accidently mark the quilt top itself. There are some wash out markers that could be used to mark up the quilts so that everyone is doing a similar pattern.