Correct base class in MFC macro?

I was wondering about the proper base class in the MFC macros,  when you multiply derive something. In the shortcutbar sample, the .h file looks like:

class CMainFrame : public CXTPFrameWnd, CXTPOffice2007FrameHook
{
DECLARE_DYNCREATE(CMainFrame)
...

and the .cpp file looks like:

IMPLEMENT_DYNCREATE(CMainFrame, CFrameWnd)
BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
...

I would have thought that the second parameter to these macros should be CXTPFrameWnd ?

I haven't used multiple-derivation with my own MFC classes much, mainly because of this issue. My assumption would be that you're okay to do this:
1) as long as the second class doesn't also derive from MFC's CObject,
2) you use the CObject derived name in the MFC macros, so the messages get passed to the right class.

Everything seems to be working fine as is, I'm just nervous about doing something wrong, so I'd appreciate a codejock comment on the issue.

Thanks very much

Warren

P.S. I'm using version 10.3.1 of the 'kit