How to Update Your Facebook Friend Lists
After you create and start using your Facebook Friend lists, you can continuously add people to them at the same time you add them as friends. When you’re the one sending a Friend Request, follow these steps to also add the person to a particular Friend List:
From his Timeline, after you’ve added him as a friend, click the Friend Request Sent button.
A menu appears asking you if you want to add that person to any of your Friend Lists. By default, your most commonly used lists will appear at the top.
Click the list you want to add your friend to.
You may need to select Add to Another List to see your full menu of lists.
If you’re the one receiving the Friend Request, you can follow these steps to add someone to a list as you accept the request:
From the Friend Request menu, click Confirm.
This adds the person as a friend. The Confirm button changes to a Friends button.
Click the Friends button that appears.
A menu appears with some options about News Feed, in addition to lists you may want to add the friend to.
Click the list you want to add this person to.
You may need to select Add to Another List to find the list you want.
If at any point you remember someone you meant to add to a list, but didn’t, simply visit that person’s Timeline and click the button that says Friends at the lower-right of the cover photo. The menu covered in the preceding steps appears, which you can use to add So-and-So to the right list.