"But having said that, it does shock me that so many adults see children as upsetting or a nuisance at a funeral, instead of as fellow mourners. (By which I mean children who are old enough to understand that someone has died and that the funeral is the 'goodbye')." Which would almost certainly not include a 3 year old in my humble opinion.
Children are wonderful but they do not need to be present everywhere, not for their own benefit or the benefit of others. When my husband grandmother died he did not want me or the kids to go, I respected that. I am sure having our quite boisterous kids present would have been very distracting for him, and although I had met her number of times and liked her, I respected my husband's wishes and did not attend.
Not everyone wants the mood lightened, not everyone wants to be distracted, and not everyone wants to think about the next generation.
Children can cause distractions and make it harder to follow what is going on, not just for those who are looking after them but for everyone else.
Maybe, just maybe the family do not have a great relationship with the nephew's wife or partner, is this a good time to try and address this? Is this appalling behaviour going to help?
tiggytape you are talking about children grieving, which I know they do. But I wonder how many children grieve for fairly distant relatives. It really depends how much the children knew their great grandmother.
It's clear you have very strong feelings about grief. And I agree about women who lost babies etc, that was awful.
But very young children do not necessarily grieve in the same way because the do not necessarily understand death in the same way. They review their grief over time. Being at a short service or not being there should not be the be all and end all. I find it alarming that the needs of very young children would be put above the wishes of the husband and daughter of the diseased.