Add option for users to favorite other users

Please make sure this added feature is mobile responsive AND the added button looks good on the mobile screen. Below are the additional details of what I need completed: 1) Allow users to favorite other users by adding an "Add to favorites" button in the user pop-up profiles. 2) Place a "Favorites" button to the left of the "View Challenges" button in the user control panel. Please make this button look similar to the "View Challenges" & "Send Referral" buttons. 3) When you click on the "Favorites" button you are to be taken into a new page that has organization for your favorite users. 4) Users are to have the ability to type the names of the sections each 'favorited' user goes into. 5) Allow the 'favorited' users to be moved from one created section to another. 6) Allow a description or note to be written for each favorited user. 7) When the 'favorited' user's username is clicked on, the pop-up profile is to show. It is already like this on the other parts of the website. Please make sure it continues to function like this. 8) Make sure if a user favorites another user, the "Add to favorites" button that is to be placed on the user's pop-up profile is greyed out to prevent from being favorited twice by the same user. ***IMPORTANT NOTE: This is a CUSTOM CODED website with the Yii Framework. You can access files with Cpanel. Please have confidence in being able to navigate the file manager to find ALL of the files that need changing or updating.