In Batman Arkham Knight: A Matter of Family DLC pack, Batgirl has to collect Jack-in-The-Boxes in order to unlock A Blade of Memory Trophy. Here are the exact location for the 5 Jack-in-The-Boxes shown below in Maps.
Firstly, complete the DLC story mode and then in free roam you collect/destroy the collectibles. The Jack-in-The-Boxes are not marked on map by default so we recommend to use the Detective vision to find them when you reach in one of the below locations. The Jack-in-The-Boxes are spawned in the outside area and not in any of the story buildings. Jack-in-The-Boxes can be activated when standing near them.
Once you finish destroying all 15 Joker Teeth…BOOM! you can unlocked the achievement A Blade of Memory.