Same content, different menu items - setting the right one active?

Hi Drupal-fans,

I have a menu-structure like this:

Category 1
Item 1
Item 2
Item 3
Category 2
Item 4
Item 2
Category 3
Item 5
Item 1

So, the same content shows on different locations. I would like to keep i.e. Cat 2 expanded, when clicked on Item 2 there, but Drupal always expands the first hit on the node (in this case Cat 1).
I tried it with different paths (drupal internally converts them to node/X) and arguments (?cat=Cat1), none worked.

Any ideas are appreciated!