I would take them. My grandfather died earlier this year and my young cousins came (10, 7, 5, 1) and were great. The 3 eldest understood what was happening and were very curious about what was happening. The 2 boys even wanted to see him one last time but we missed the viewing before the service. A DVD was made of photos to music and the eldest girl loves watching the DVD. It was actually during the morning tea after where the kids started getting ratty. It was wet and the area was small and loads more people than expected turned up. I think it's a perfect opportunity to explain death and the circle of life plus gives your DD the perfect opportunity to say one last goodbye.