1.存储父示例的引用
1.使用Instantiate(Object original, Vector3 position, Quaternion rotation, Transform parent)方法示例化父示例下的第二个预制件示例
下面是我的测试代码，运行良好：

public class PrefabParentTest : MonoBehaviour
{
    [SerializeField] private GameObject _prefab1;
    [SerializeField] private GameObject _prefab2;
    void Start()
    {
        var instance1 = Instantiate(_prefab1, Vector3.zero, Quaternion.identity);
        var instance2 = Instantiate(_prefab2, Vector3.zero, Quaternion.identity, instance1.transform);
    }
}

或者，您可以使用Transform.SetParent（不建议作为第一个）来实现相同的目标：

void Start()
 {
        var instance1 = Instantiate(_prefab1, Vector3.zero, Quaternion.identity);
        var instance2 = Instantiate(_prefab2, Vector3.zero, Quaternion.identity);
        instance2.transform.SetParent(instance1.transform);
 }

参考文献：

• https://docs.unity3d.com/ScriptReference/Object.Instantiate.html
• https://gamedevbeginner.com/how-to-spawn-an-object-in-unity-using-instantiate/
• https://docs.unity3d.com/ScriptReference/Transform.SetParent.html