The A Matter of Family Add-on for Batman: Arkham Knight has 8 achievements.
Rescue your father.
Free the hostages at the Ghost Ship.
Free the hostages at the Merry-go-round.
Free the hostages at the Ferris Wheel.
Defeat 4 enemies within the duration of a single scare effect.
Destroy all Teeth, Balloons and Jack-In-The-Boxes.
Defeat 15 enemies using any type of hacking.
Uncover the secret history of the park.