How to choose random spawn point and spawn within its limit?

Greetings,

I'm trying to have my GameManager object (wave spawner script) spawn enemies at set locations -- and at a random location inside them.

I have a public Transform[] Spawnpoints; array in my manager in order to create more spawn points through the inspector. If I want to spawn enemies at these positions, then I can simply use this function:

 private void SpawnEnemy(Transform enemy)
     {
         Debug.Log("Spawning Enemy" + enemy.name);
         Transform SP = SpawnPoints[Random.Range(0, SpawnPoints.Length)];
         SP.position = AreaSpawn.SpawnLocation();
         Instantiate(enemy, SP.position, SP.rotation);
     }

I use an empty game object to choose my spawn locations, which I've turned into a prefab. However, I have a separate script that is attached to the spawn locations that looks like this:

 using UnityEngine;
 
 public class AreaSpawnPoint : MonoBehaviour
 {
 
     public Vector3 Center;
     public Vector3 Size;
 
     public Vector3 SpawnLocation()
     {
         Vector3 Position = Center + new Vector3(Random.Range(-Size.x / 2, Size.x / 2), Random.Range(-Size.y / 2, Size.y / 2), Random.Range(-Size.z / 2, Size.z / 2));
         return Position;
     }
 
     private void OnDrawGizmosSelected()
     {
         Gizmos.color = new Color(0, 0, 1, 0.7f);
         Gizmos.DrawCube(Center, Size);
     }
 }

In a nut shell, the public Vector3 SpawnLocation() returns a random location within the cube every time it's called. I apply this script to my spawn location objects, and create a specific size spawn area where they are allowed to spawn. (see below to get an idea)

Problem My issue is I'm not sure how I can choose a random spawn location and use the random spawn location inside it. Currently, (if you look at the screenshot above) I can reference only one of the spawn location objects and it works with just that one spawn location. How can I reference all of the locations? I'm sure there's a way, but I'm not quite sure how.

Thanks