Trying to add guitar chord diagrams to my lead sheet, but can't find the right menu item and/or short cuts to do so. Is this a flaw in Sibelius 6 (other Sibelius 6 users I know seem to have the same problem) or are we overlooking something? Please help. Sincerely, Bodegro.

First of all, why are you using Sibelius 6? It's way out of date. The current version (Sibelius Ultimate) is way better in all respects. It's well worth the cost of upgrading. And it most definitely supports chord symbols and just about anything else you could want on a lead sheet. Why don't you try *** reading the manual *** ? I don't know about Sibelius 6, but Sibelius' manuals are usually fairly good and they wouldn't leave out something as important as chord symbols. There is a HUGE amount of info in the the Sib. Ultimate manual. Also look at the tutorials, to get started.

Apparently the relevant command is found in the Create menu: Create->Other->Guitar Scale Diagram (see pp135-136 in the Sibelius 6 Reference PDF)