Object property is not valid when in blueprint child class

I thought doing like you suggested, but it wouldn’t be ideal.

When a player joins the game, I spawn a character programatically like this:

void AInGame_GameMode::PostLogin(APlayerController* NewPlayer)
{
	Super::PostLogin(NewPlayer);
	if (AInGame_GameState* InGame_GameState = GetGameState<AInGame_GameState>())
	{
		InGame_GameState->SpawnPerson(NewPlayer);
		Cast<AInGame_PlayerController>(NewPlayer)->SetInputModeGameOnly();
		// Here, I want to get the spawned character and load its inventory, hunger, thirsty, money etc. But the "Inventory" property is null.
	}
}

I need to access the inventory property just after I spawned the character, so I need do instantiate the UInventory object at the APerson_Character constructor.