Reporting on cells common to different worksheets

Thanks to Wendy for a great Intermediate training on Friday. But I have a question she thought the Forum could help with!

I have a workbook with severalworksheets in it, listing the different services used by three Clients: A, B and C. On a 4th worksheet, I want to be able to report on which services they all use, as well as which ones only they use. In an ideal world, each common service would also pull some other associated data with it.

I am basically looking to create a report which does the same thing as a Venn diagram, showing where the commonalities are (it doesn't need to look like a Venn diagram!). I have a sample workbook I can share if anyone wants to have a go.

Thanks very much in advance for your collective wisdom!