Drupal 7 force active menu item
The Menu position module will solve your problem. 


  Often times site builders want certain types of content to appear in a specific position in the navigational menu. The simplest solution, adding all of that content individually to the menu system, has performance and usability issues. (Imagine hundreds of menu items added to one spot in the menu.)
  
  This module allows for the creation of rules that will dynamically add the current page into the menu system at the requested spots.