# Overview

Sometimes you want to synchronize Entities that are connected to other Entities. These relationships can be references between Entities, but they can also involve direct parent-child relationship between game objects, or more nuanced use cases.

Here's a guide for what technique to use, depending on the situation:

* If you have an Entity that needs to keep a nullable reference to another Entity, use a normal [Entity reference](https://docs.coherence.io/0.9/connected-entities/entity-references). This includes any existing MonoBehaviour that has GameObject or Transform fields that you want to synchronize over the network.
* If the Entities are placed in a hierarchy, use the techniques for [parent-child relationships](https://docs.coherence.io/0.9/connected-entities/parent-child).