• You can sometimes add a Facebook friend by specifically looking for him and then adding them.
• Log in to your Facebook profile.
•  Go to one of the two persons you want to connect with's profile.
• In the left panel of the screen, scroll down until you see the 'Suggest Friends' link. This displays in this panel directly below the list of some of your friend's friends. When you click this link, a new window will open with a list of all of your Facebook friends.
• Select the buddy or friends you'd like to recommend to this person. When you're finished, click the blue 'Send Suggestions' button.

Read More: How can you see connections between two people on Facebook?