Well, hate to break it to you but there will most likely come a time when one of the 3A will want to switch to another coach. It‘s insanely hard to have two direct rivals at the same rink, with the same coach and it works in very few instances (Hanyu and Fernandez being one but that was a truly unique case). Not to mention three girls, who, at one point will all be capable of winning the biggest prize. It works at the moment because stakes aren‘t so high and they are still very young but even now we‘ve seen hurt feelings and tears. I admittedly kind of like this whole 3A business, the thought of them being close friends and competitors at the same time and all that. But they won‘t be 3A forever, they will want to be Alexandra Trusova, Aliona Kostornaya and Anna Shcherbakova. And I don‘t know if keeping them at the same rink then, when they‘ve matured mentally, will work. Actually, I‘m pretty sure that it won‘t. Just saying.
They‘re 14, as far as I know. Sasha and Anna are 15, Aliona 16. You need to be 15 by a certain date before you‘re allowed to debut as a senior but I always forget which one. I believe Sinitsyna (and Kanysheva) will be old enough for senior next year, though. No idea about Frolova.