Context: [https://unity.slack.com/archives/C0214P2C947/p1696623271668409]

With thanks to [~philippe.stamand] for the find!

Repro

1. Create a ghost with children.
2. Have those children spawn additional entities.
3. Have a code-based default variant with SendDataForChildEntity = false.
4. Observe how the additional children default to replicating.
5. Also observe how attempting to manually fix the children results in the exception:

{code:java}
GetOrAddPrefabOverride:

if (gameObject.GetInstanceID() != entityGuid.OriginatingId)
{
var didMatchChild = TryGetFirstMatchingGameObjectInChildren(gameObject.transform, entityGuid, out var childGameObject);
var error = didMatchChild ? $"It matches a child instead ({childGameObject}). Overrides MUST be added to the Inspection component of the GameObject you are modifying!" : "Unknown GameObject.";
throw new ArgumentException($"Attempting to GetOrAddPrefabOverride for entityGuid '{entityGuid}' to '{this}', but entityGuid does not match our gameObject! {error}");
}{code}