I loved the story about your grandson :D :D Sounds like something my 5year old grandson would say. I can't help you here as I've never ever done any machine quilting. Only hand. If I was hand quilting it would be in the ditch,then cable on the border.
My grandson (the 5 year old) only lives 2 hrs. from us so he's been here enough since I started his quilt, he gives me his 2cents worth about what he wants on it. LOL