Ah ah, i didn't really react to the news, but none of the articles about it seem to mention that Sara was played by another actress lol.
Granted, she was just in the pilot, but she still has a huge impact on the Lance Family so people remember her.
They could have just recasted her but it would be very soapy, even for Arrow.
So, i don't mind the idea, but all this still seem overcomplicated.....and a bit uneccesary.