I'm probably the only one out there on this... But in my opinion my child doesn't make those types of decisions yet. This trip is not about her. It's about Grandma. If I was dying I would be heartbroken if my grand baby didn't come, because she was having a baby fit/control issue. I think it should be a lesson for her that life isn't always about what we want to do, but a sacrifice sometimes for the good of the whole.
That is my opinion and either way I support you on what you decide! I would like to know how this all turns out! =)