I am sorry for your niece, my best thought are with her mother. Also her case was not from natural cause. It was an illness that can't be natural. I don't know if nowadays there's someone who dies of natural cause anymore.
Yes, I can imagine (although imagining will never be as living it) it's something awful. And that's why I always thought why.. how could be possible that all the Jacksons (let's say some: 1,2, are grieving differently and they don't show suffering.. but all of them? all?) show no real suffering towards this and it was one of the first thing that got me into the hoax possibility, last december, besides other things. I know there are a few people, rare, who don't show their grieving but those are just rarities. I've never seen in my life someone who lost his/her child/brother/parent and who was laughing his/her ass off 2 days after the death, or going shopping as it would have been another day, another evening. I am aware this can be possible, that there might be people like this but they must be rarities.. And I just don't buy the fact that all the jacksons from partents to brothers to children would be part of those rarities who never grieve or show a suffering.