Hide a Qualified tab dynamically using getVisible

I have a global "add-in" for Word 2007 that creates a new tab ("A") on the ribbon with various groups, buttons, galleries, etc. Other templates interact with tab A, usually adding buttons specific to their content. I can't change this existing set-up.

Since the tab is shared it is defined by a idQ property. This appears to disable the getVisible callback.

If I change the tab to have an ordinary ID tag then getVisible works just fine.

Is there some way round this restriction?

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What I want to end up with is two separate tabs A and B created from separate "add-ins", both tabs will be shared but in different namespaces. A has a distinct set of templates that belong with it. B also has a distinct set of different templates. There is no crossover between A and B's templates.

On tab A I want a button that toggles B on/off (using the registry to store the user's choice). On tab B there will be a toggle for tab A.

The reason for this is that some users need both tabs but most need one or the other. There is no other way to determine who should have what (via AD say).

btw. I can't manipulate the .dotm file directly (targeting the xml itself via an unzip/modify/zip) as the users don't have write rights over the file.

Thanks

Simon