This utility lets you easily combine two scenes into one.

MultiScene.cs

using UnityEngine;
using UnityEditor;
using System.IO;


public class MultiScene
{
	[MenuItem ("File/Combine Scenes")]
	static void Combine ()
	{
		Object[] objects = Selection.objects;

		EditorApplication.SaveCurrentSceneIfUserWantsTo ();
		EditorApplication.NewScene ();

		foreach (Object item in objects)
		{
			EditorApplication.OpenSceneAdditive (AssetDatabase.GetAssetPath (item));
		}
	}


	[MenuItem ("File/Combine Scenes", true)]
	static bool CanCombine ()
	{
		if (Selection.objects.Length < 2)
		{
			return false;
		}

		foreach (Object item in Selection.objects)
		{
			if (!Path.GetExtension (AssetDatabase.GetAssetPath (item)).ToLower ().Equals (".unity"))
			{
				return false;
			}
		}

		return true;
	}
}

Whoa it looks intresting!