Hi Djaydino,
no, no, no, those red X's are already in the scene, they don't need to be spawned on runtime, i justed turned on their renderer so they can be seen. They are already named A1, A2...their location will be used for spawning enemies on runtime, and enemies need just need a vector3 or gameobject reference.
Wow, that seems a bit complicated, but i'm sure it's easy, i'll give it a shot and let you know!