How to reference a prefab in a class array from a json

I am populating a JSON with an array of classes. Each class contains another array of classes that store variables about an encounter-able event. One of the variables in the class is a public gameobject which contains a prefab with a 3d model component. If I reference the prefab in the JSON is stores it as a volatile instanceID that changes every time the editor is re-launched. The system will work perfectly until the instanceID changes. I'm trying to set it up such that when I add a new event in the future, I don't have to change things in two places. I was thinking of making an independent public gameobject array in an eventmanager script. However that will mean making a new event will require increasing the class array, entering the data. Then adding the prefab to a separate game object array which doesn't sound like much but when there are hundreds of events it will become tedious. Here are the classes:

 [System.Serializable]
 public class ExternalEvents
 {
     public ExternalEvent[] m_ExternalEvents;
 }
 
 [System.Serializable]
 
 public class ExternalEvent
 {
     public GameObject m_EventObject;
     public string m_EventName;
     public string m_Description;
     public int m_ExternalEventCode;
     public int m_MinProbabilityRange = 0;
     public int m_MaxProbabilityRange = 0;
     public bool m_IsUnique;
 }

Here is the method that instantiates the prefab when an event is encountered.

 void CreateRandomExternalEvent()
     {
         int i = Random.Range(0, 1000);
         m_ExternalEventOffset = new Vector3(Random.Range(25, 40), 0, 0);
 
         for (int j = 0; j < m_ExternalEvents.Length; j++)
         {
             if(i >= m_ExternalEvents[j].m_MinProbabilityRange && i <= m_ExternalEvents[j].m_MaxProbabilityRange)
             {
                 Instantiate(m_ExternalEvents[j].m_EventObject, m_MainShip.transform.position + m_ExternalEventOffset, Quaternion.identity, m_LevelObjects.transform);
                 m_EventsActive = 1;
                 break;
             }
         }
     }

So ultimately the questions is, what is an easy and elegant way I can reference the prefab that won't break every time the editor is re-launched. I understand this isn't so much a cut and dry technical question it's more of a request for a suggestion but I don't know anyone who knows a lot about unity so I thought I would try the official forums.