You are right. There is no right/wrong answers here. I am an educator and while working on my Master’s degree in education I took a class about grief in children. It was a heavy, but great class. Basically, you should do what you feel your children are capable of handling. However, try not fantasize death and be careful with the wording you use. Young children are not capable of understanding abstract thinking yet. It is best to stick with facts when you are discussing death with children (Uncle’s body stopped working correctly and he died.). Stay away from describing it as the person sleeping forever. The children might be afraid to fall asleep.
In my personal life, I have always asked my kids what they felt comfortable doing. Even at a young age, I feel like they are able to make the decision themselves.
We lost about 6 close family members within about a year or so when my younger daughter was about 4-5 years old. When I sat down to talk to her, I asked her if she had any questions about what was going on I would allow her to ask anything she wanted to know. When my stepdad (she was VERY close to her papa) died, she had some pretty tough questions. She was 4 at the time, and asked what would happen next. Then she followed that question up by asking if they were going to throw papa in the trash. I told her that we do not throw people in the trash when they. I told her that the coroner would come pick up his body from the hospital and they would cremate him. She asked what that meant. I told her that they were going to turn his body into ashes and we were going to get some of the ashes so we can always have him near us. She even asked how a body turns to ashes. It broke my heart to explain that they put the body in a machine to burn it and that turns it to ashes. She was much more fine with hearing it, than I was fine with explaining it to her. I tried to make it short, concrete answers to only give as much info as she needed to understand. She ended her line of questioning with that question and then said, “Mommy, when you die I will cremate you so I can keep you close to me forever too.” I was always scared of cremation myself and was never interested in getting myself cremated (obviously I wouldn’t have much choice since I would be dead, but I have always been pretty good at telling others what decisions I would want to be made in my final moments of life.). However, this special (and difficult) conversation with my 4 year old child opened my eyes and re-evaluate things to the point that now I am fine with my loved ones cremating me. She was able to give me a different view point.
When she was maybe 10 years old, her friend’s brother had gotten hit by a drunk driver while crossing the street. We were invited to the viewing and services. My older daughter (who was the same age as the brother) decided that she did not want to go to the viewing because she wasn’t ready for it, but my younger daughter (the 10 year old) decided she wanted to go. I respected both decisions and took my 10 year old, but left my 16 year old at home.
Long stories short, maybe you should just ask them and see what they are ready to talk about and if they are ready to attend the funeral. You can describe what a funeral will be like and the expectations for behavior at a funeral so they can make a decision.