It's from the Requirements for those kinds of Fireteam. http://infinitythewiki.com/en/Fireteam:_Haris Requirements In addition to the Fireteam Common Requirements, a Fireteam: Haris has to fulfill the following specific Requirements: Only those units specified on their Sectorial Army List can compose a Fireteam: Haris. At least one of the members of this Type of Fireteam must have the Fireteam: Haris Special Skill. A Fireteam: Haris is composed of two or three members. A player can only have a single Fireteam: Haris on the table, unless a Scenario Special Rule or some other Special Skill state otherwise. She's fulfilling bullet two, and the equivalent bullet in a Duo. Yes, just like all the existing Fireteams where you can swap everyone out.