Add multiple databases at load time to the master Dialogue System Database.

DialogueDbManager.cs

using UnityEngine;
using System.Collections.Generic;

namespace PixelCrushers.DialogueSystem.Adnc {
	public class DialogueDbManager : MonoBehaviour {
		[Tooltip("Allows you to add multiple databases to the current Dialogue System. @IMPORTANT Make sure to run the ID assigner to prevent overwriting.")]
		[SerializeField] List<DialogueDatabase> db;
		
		// Use this for initialization
		void Awake () {
			foreach (DialogueDatabase d in db) {
				DialogueManager.AddDatabase(d);
			}
		}
	}
}