# 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/0.4.14/connected-entities/entity-references). This includes any existing MonoBehaviour that has GameObject or Transform fields that you want to synchronize over the network.
* If knowing about an entity implies that you should also know about some other (connected) entity, you might need to use the [ConnectEntity component](https://docs.coherence.io/0.4.14/connected-entities/connectedentity-component).
* If the entities are placed in a hierarchy, use the techniques for [parent-child relationships](https://docs.coherence.io/0.4.14/connected-entities/parent-child-relationships).