NPC usually don't have family or home, appears out of thin air into your town. The merchants in world adventure actually do have family and a home.
The World Adventure xpac has been out for a long time, and if those merchants counted for NPC friends, I'm sure the list would have been updated by the team. Since I don't see those merchants on the list, I'm going to say they are not counted. Safer to stick with the list? There are 34 on that list, more than enough for the requirement.