To add a friend on Facebook but not let anyone else see, go to your activity log, click on the Friends option, uncheck the option to post about your new friends, and save. No one is able to see when you add new friends.Continue Reading
Go to your Facebook profile, and click on the Activity Log button located at the top of your Timeline.
Click the Friends option on the menu, located on the left side of the screen. Click the Options icon located on the right side of the page, and uncheck the box that says New Friend Reports.
Click the Okay button at the bottom of the menu to save the settings. None of your friends are able to see when you add new friends now.