using UnityEngine;

using UnityEditor;

public class CreateNesting

{

[MenuItem("Prefabs/Nesting/NestBInA Via Instances")]

static public void NestBInAViaInstances()

{

var goA = (GameObject)AssetDatabase.LoadMainAssetAtPath("Assets/Prefabs/A.prefab");

var goB = (GameObject)AssetDatabase.LoadMainAssetAtPath("Assets/Prefabs/B.prefab");

var instanceA = (GameObject)PrefabUtility.InstantiatePrefab(goA);

var instanceB = (GameObject)PrefabUtility.InstantiatePrefab(goB);

instanceB.GetComponent<Transform>().parent = instanceA.GetComponent<Transform>();

PrefabUtility.RecordPrefabInstancePropertyModifications(instanceB.GetComponent<Transform>());

PrefabUtility.ApplyPrefabInstance(instanceA, InteractionMode.AutomatedAction);

// Clean up

GameObject.DestroyImmediate(instanceA);

}

[MenuItem("Prefabs/Nesting/NestBInA Via Content")]

static public void NestBInAViaContent()

{

string path = "Assets/Prefabs/A.prefab";

var goB = (GameObject)AssetDatabase.LoadMainAssetAtPath("Assets/Prefabs/B.prefab");

var instanceB = (GameObject)PrefabUtility.InstantiatePrefab(goB);

var root = PrefabUtility.LoadPrefabContents(path);

instanceB.GetComponent<Transform>().parent = root.GetComponent<Transform>();

PrefabUtility.RecordPrefabInstancePropertyModifications(instanceB.GetComponent<Transform>());

PrefabUtility.SaveAsPrefabAsset(root, path);

// Clean up

PrefabUtility.UnloadPrefabContents(root);

}

}