New idea, feedback appreciated

[ggg-2 3,549]

While getting to know her new student's old friend better, Twilight learns that Sunburst has an older twin sister......and that his last name happens to be Shimmer!

[Snowbound 17]

I don't think it really works for twins to be older and younger than each other, unless you mean slightly older than Sunburst, but I'm sure it's possible for twins to be separated at birth; it's happened before. (I just realized you said Shimmer and not Glimmer) OMG, that's awesome! I've never thought about that before. Maybe Sunburst and Sunset Shimmer could be meant to be brother and sister to be revealed later in the series itself; but, it's unlikely considering how, for some reason, there is only one Sunset Shimmer to be shared between the pony and human universes and she prefers to reside in the human universe.