The Skeleton_Warrior sprite and the skeleton animation sprites are not connected to each other. Pin only makes them move together, but it doesn't really link them.
You need to add them to a container (in properties on the left panel). Then each Skeleton_Warrior instance will be linked with the animation sprite. You only need to create one object, all other objects in the container will be created automatically. And when one object in the container is destroyed, all other members will also be destroyed.
Most importantly, all members in the container will be picked in events. If you pick Skeleton_Warrior instance (for example by checking its LineOfSight), its animation instance will also be picked.