thanks. 
yes, 3 years is a little on the longer side. most live not far more than 2, but it has been known for a rat to live well past 4. It's always hard to teach kids about death, and I dont have any kids and plan on never having any so I have no idea what the good thing to do about that would be. I guess the good experiences are worth having the bad ones.
Because the Princess Royal was born into a small family of older parents, each death hits her particularly hard. I read an article about explaining death. It said that death is a part of change and part of our sorrow is a fear of loneliness and missing the person. If things were to stay the same (no death) then there would be no new people in our lives. Sort of like, "If Grandpa were still alive, then we'd be living in 2005 and we wouldn't have your new sister."
When the oldest was about 5, we had a couple of young deaths in a row, and I read her
Frog and the Birdsong. She asked for it time and time again. It has both the sadness and realising it is a final end, and the notion of life going on, and things coming in place of what is lost.
We also talked about it a lot. And both kids were playing funeral for months.
