A.P.
Wow, that is some heavy duty tragedy. My heart goes out to you and the family.
In my opinion, I'd want my daughter at a memorial or funeral for me. I think children bring a source of light and renewal to somber events, and that they remind us, in good ways, of the people who have passed on. I think having a child at a funeral can be healing, and become a celebration of a life, even during mourning.
Also, I think that if a child is kept away from the funeral or the information about a death is somehow not open, they will resent it later. I grew up with a friend whose father had remarried after her mother died and she was told she had a new mother, no one really explained what happened and why she would every possibly "need" a new mother as a tiny child. She still remembered the gist of what they told her, "old mother is gone, but now you have a new mommy who loves you very much", and only learned that her mother had actually passed away when she was a much older child. Her family didn't realize how abandoned she had felt or what memories were etched into her psyche. In my opinion, most kids do feel abandoned after a parent dies, to some degree, so it's helpful to say "goodbye" no matter how old they are. My friend was sent to a friend's or neighbor's home for the funerary services and just remembers the day that everyone left the house wearing black.