When determining heading hierarchy, you should also consider how the heading placement as well as the print font. In your situation, although the print font is the same the placement is different. I believe this would allow you to make the Think, Talk, and Write headings cell 5 as long as all Think, Talk and Write headings were consistent.

However, if you are concerned about them all being the same, the headings Think, Talk, and Write are independent enough to be there own centered heading.

Mike