I can't find my child sim

Product: The Sims 4
Platform:PC
Which language are you playing the game in? Français
How often does the bug occur? Occasionally (10% - 49%)
What is your current game version number? the latest
What expansions, game packs, and stuff packs do you have installed? Everything except Batuu
Steps: How can we find the bug ourselves? I have no idea
What happens when the bug occurs? In the family, the mother was an elder and her daughter was a child. The mother passed away and the child was nowhere to be seen. I can only see the child in the family tree from the child's siblings
What do you expect to see? I would like to have my sim back
Have you installed any customization with the game, e.g. Custom Content or Mods? Never used.
Did this issue appear after a specific patch or change you made to your system? Neutral/Not Sure 

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Hello,

So here is the situation :

In the family, the mother was an elder and her daughter was a child. The mother passed away and the child was nowhere to be seen. I know that children can not be left alone in the household.

I can only see the child in the family tree from the child's siblings;

I tried resetting the child but the message was "Sim not found", I can't find the child in manage household either.

I hope someone understand my issue here, therefore if it is not solvable I won't mind. It is still weird that my elder died while her daughter was a child, I thought the elder could not die if there was a child in the household, so I did not worry about it at first.

Thanks,

Nolwenn