@ossobuco,
Yeah, I know what you're saying. In this particular case, which is a bit unusual, I don't think that I'd provide any particular comfort to her. She's very very active in this community and has several concentric circles of people around her. The closest circle is made up of probably ten or so people, and I'm two or three circles out, in the company of literally hundreds of people. I don't think my being there or not will make any real difference to
her.
I definitely think that showing up is the thing to do at this point, when I was talking about the memorial page it was in terms of in addition to going, not instead of.
My main concern was imposing/ overstepping boundaries, but I'm reassured from this that showing up at a funeral without an invitation is not usually a problem.
At this point I'm thinking show up and also cards for each sister (which is another question, send the cards? is there a place for them at the funeral? I wouldn't want to hand them over in person, seems like that'd be cumbersome).