[TYPO3] Conditional menu

[Brian]

Hello all. On my site I have a menu structure that is pretty typical in that it shows pages on the same level and any subpages of the active page. Suppose that on one particular page (id = 15 suppose) that I do not want to show any of the subpages even on the active page but I still want to show the pages on the same level (suppose that is level 3). Now for a subpage of that page (level 4), I do not want to show pages on level 4 but only the pages on level 3 (so essentially the same menu that its parent page showed). Finally, on level 5, I want to only show the level 5 pages and nothing more. I know that I could set this manually on each page but the number of level 4 pages is too large for this to be feasible. 

Currently what I have is all pages on level 3 or below only showing the level 3 menu which is essentially what I want except for level 5. What I would like to do is to set some TypoScript on the level 3 page that would apply ONLY to its subpages. I was thinking that there might be a way to do this with a conditional statement saying if the ID of the page is not whatever the level 3 page is (I can set that manually because there are only 3 of them). Thoughts?