Well, I decided to throw myself on my sword as it were and call my sister and apologize for the misunderstanding. It turns out that my sister wants to have the 1st Communion on Saturday because they have friends coming in from Ohio and she wanted to make it easier for them. The 1st Communion on Saturday is at 4:30pm (5:30 my time), meaning I would completely miss the Saturday performance of the musical. And of course, all the cleanup afterward. So I asked my sister what time was available on Sunday. Apparently there are two possibilities: 9:30 (8:30 Chicago time) or 11:30 (10:30 our time). And sister dear doesn't want to do the 11:30 since that would also inconvenience the Ohio friends. So it looks like it's either Saturday or the early Sunday Mass, she's going to let me know.....
Then she tells me that she was thinking of asking for her money back. It seems that she contributed part of the money that paid for the Johnny Mathis concert tickets, yet she never asked when the concert was either! Since I was not involved in the concert at all, I didn't know what to say to that (I'm honestly still a little peeved that the sister who bought the tickets completely shut me down when I pointed out that it was the same weekend as my son's musical).
I spoke with my mother prior to calling my sister and I think we've pretty much agreed that we're going to see if we can somehow drive up after finishing at the musical, if the 1st Communion is on Sunday. If it all works out, we'll get home from the musical around 1:30 am, shower and change clothes, then drive over to my parents' house around 2:30. Hopefully they'll be home from the concert by then and we'll all leave for Michigan and get there sometime around 7:30am their time. Which may leave enough time to get a one hour nap so that I don't fall asleep during Mass. And then later on Sunday we have to turn around and drive home since DS has a band concert on Monday and has to be in school that day to participate in the concert. If my sister sticks with the Saturday date, then I guess she'll be celebrating with the Ohio friends.