OP, 'However, I don't get it that she is making people who are her friends go to her sister's memorial.'. Er, perhaps because she needs the people who are her friends to provide support.
You refer to her grief and need for support as 'weird'. You think the memorial service is a 'palaver'. You believe that her grief is 'fake'?
Sorry, but this really angers me. My mother lost her brother at a very young age, 35 years ago. She still mourns. She relied on many friends at the time, as her immediate family were torn apart by grief.
My father has lost three siblings. The last of which being his brother, last year. My uncle passed away horribly, and my father and some of his brothers and sisters were there to witness it. They were traumatised. My uncle had lived abroad for over 40 years, his funeral took place in the country where he had lived, where his wife and children lived. We had a memorial service here, for him. So many people, who had lived down the road from their family 40 years ago; who had never met him, but knew members of his extended family; who were schoolmates of his decades ago, showed up to the memorial service. My friend's husband's father was there, because we had met at several weddings/parties, and he knew it was important to my family and I. My father and his family took huge comfort in the fact that so many people showed up to pay respects to their brother.
In short, if you care about your friend at all, you will be there to support her. You will also stop insinuating that she is using her sister's death to garner sympathy or gain attention. That is nasty.
Funerals are awful, nobody can dispute that. I, at 26, have sadly attended the funerals of 4 friends. All were painful. However, I attended them, as it is respectful, and a chance to say goodbye. This memorial service will not be terribly painful for you, as you freely admit that it is not a close friend of yours who has passed. So, go, be there for your friend, and please swallow your nasty thoughts regarding this being 'weird' and a 'palaver'.