I've already told her that the elderly dbro won't be going and doesn't want to. I'll try to make sure any discussion goes through me as the dbro gets upset and stressed. He's quite happy relieved about his.
That is really sad. I have a relative who is a bit like this and, most of the time, it's easier just to go with what they want. It's when someone else feels that they need to put their foot down that things get really difficult and I think that's made worse by the fact that it doesn't happen often.
If you feel that the elderly relative really need to be protected from this could you, as a family, express your concerns, perhaps by writing to them, and, ultimately, say that you won't participate in an activity in memory of someone who has died at the expense of the well-being of someone who is still around?