I think the "cross" feeling relates to the idea that somehow the funeral makes the death real, when for many here, who lost the partners when their children were young, nothing was needed to make it real for the children - they were living that reality hour by hour.
Thankfully I have never been in that situation, but I do see where they are coming from.
In the instance with the OP, I do think that if this lass has asked to go then she should be allowed to and should have some small role in the proceedings. But I do think that her parents should be the ones to make the decision.
Disappearing contributors - part 2
Police Probe Andrew Over Sex Offences

but I still think he would have wanted to be there.