I think I understand how Yuuri feels in regards to the situation with her sister and all the regrets she has, though for me it was early adulthood instead of childhood. It's a painful feeling because while you don't want to say your grievances out loud (in part because you don't want to admit they exist), specially to the person they regard and even more if it's not their fault, it is something you need to accept and process, you can't just live ignoring it. I still don't think it's fair on Tsumugi though, specially considering how much she's grown, and the fragile spot she is right now, though unfortunately that's exactly why Yuuri kinda blew up. I feel sad for both of them, but that's how development goes, let's be positive.
The expectations usually go to the Futaba sisters meeting each other in the competition, but considering how this story has been going, I wouldn't be surprised if one or even neither of them make the cut to go on stage, maybe even ending with Tsumugu being eliminated for health reasons (directly or indirectly). This would be extremely unfair. but the author so far hasn't been afraid to twist the knife, and sometimes that's just these things go, so let's see how this goes.
We have the whole competition to see, and considering it's team vs team, with the victor gaining immunity for the whole team (correct me if I'm wrong), the elimination will be quite difficult to decide, no one's safe (though plot armor, and recent circumstances matter of course, some are eliminations are really unlikely).