I also agree with the use of rectangles. They are an organization tool and are meant for this purpose.

The only thing I have to watch out for with rectangles is making sure that what you want inside the rectangle is actually in there. Note the name of the rectangle object. Then after placing your textboxes inside the rectangle select each textbox one-by-one and look at the object properties. There is a property called "parent". If the textbox is inside the rectangle the value of parent will be the object name of the rectangle. Sometimes it can take some trial and error to ensure your objects are inside the rectangle.