Ability to show items on same level if active menu level has children

Here is my issue:

For Example:

Menu1
-item1
-item2
-item3

Menu 2
Menu3

-When I click on Menu1 (My right nav menu displays only item1,item2,item3)
-when I clcik on Menu 2 (My right nav menu displays

Menu1
-item1
-item2
-item3

Menu 2
Menu3 )
(For this I commented
/*if ($level == 'child') {
$tree = array();
}*/

Actual Problem : Even if the Menu Item is having children I want to stick with the original Menu - In one word Unique Menu Navigation for all the menu items)

Please help me how to fix this problem.

Thanks
Revathi