navigation with children, grandchildren but only on certain pages

Hi.

I am using WP as a CMS.

I want to display a navigation on a single page of itself, its children and grand children, like this:

Studio (parent)
– Services (child)
– Location (child)
– – floor plan (grandchild)
– – the rooms (grandchild)

Cases (parent)
– Advertising (child)
– – Case A (grandchild)
– – Case B (grandchild)

Contact (parent, no children)

etc. etc.

But I want to exclude other parents and their siblings, ie. I don’t want Contact or Cases in the navigation when I am on the Studio pages.

I have tried using the code from the codex, but that will not display parents or grandparents when on a child or grandchild page.

Hope there’s a genius out there with a few moments to help a guy out.

Thanks.