Navigation Panel customization based on MenuItem

Hi,

I have two pages named as Page_1 and Page_2, both visible in navigation panel. Both have some sub-pages (hierarchy is given below). I have disabled the navigation panel, and show both pages horizontally on the top using MenuItem as Page_1 and Page_2.

Now what I want to achieve is, clicking on Page_1 on top should make visible only Page_1 and its sub-pages, from navigation panel, not the entire navigation panel. Similarly, clicking on Page_2 on top should make visible only Page_2 and its sub-pages, from the navigation panel, not the entire navigation panel. Is it possible to achieve? If yes, how can I do so?

Page_1
--SubPage1_1
--SubPage1_2
Page_2
--SubPage2_1
--SubPage2_2

Note:- I am not sure if this is a bug, or the way it is developed.
Thank You