A Flash/Supergirl Cross-Over Is Now Official

When it was first announced that Supergirl was coming to television, and that it was going to have Greg Berlanti and Andrew Kreisberg as executive producers, everybody began to wonder if the show would take place in the "Arrow-verse."  CBS and the EP's quickly downplayed the idea, and said that she would be apart of her own universe.  I still think that's going to be true, even with the announcement that Grant Gustin's Flash is going to appear on Supergirl on March 28 this year.  Here was the statement given by Berlanti and Kreisberg on the crossover, and then I'll explain how they'll still be able to keep their respective worlds separate:

"We are so incredibly excited to announce something that we have dreamed of happening since we starting making Supergirl – The Flash and Supergirl are teaming up!  We want to thank Grant Gustin for making the time to come visit (on top of his already immense workload) and all of the folks at CBS, The CW, Warner Bros. and DC for working this out. And finally thanks to the fans and journalists who have kept asking for this to happen. It is our pleasure and hope to create an episode worthy of everyone's enthusiasm and support.”

So how will they be able to pull this off while keeping their own worlds separate?  The Flash has introduced the reality of alternate universes, and it also seems that Flash is going to be traveling to these alternate Earths in his upcoming episodes.  So...what if one of these Earth's will be the one that Kara Zor-El is apart of?  Makes sense, right?  This way, they can do the cross-over without screwing up any of their own story lines and making things more confusing in the long run for every show involved in the "Arrow-verse" (i.e. Arrow, The Flash, Legends of Tomorrow).

I might be wrong on how they plan to handle the cross-over, but this is the one that makes the most sense.  Also, The Flash is a better fit to use as a cross-over show, as opposed to Arrow, because The Flash is a "lighter" show that compliments Supergirl, unlike Arrow which is darker and more gritty.  How ever they handle it, we won't have to wait long to see how it happens!