I'm currently working on a book where the client has requested that certain sections of text are inside a gray box. I figured I could but that text inside a text box and place that text box inside the main body of text, so the box is uniform and not a floating shape behind the text box that I need to worry about during editing. However, I run into issues when the gray box text spans more than one page. Is there a way to thread text boxes that are placed inside another text box? The little box is there on the corner of the gray text box but I cannot click it to thread it to another 'placed' gray text box. I'm also open to other solutions.
I'm currently working with Adobe InDesign CS6.