If they have cast the role for maria and royce king the second. does that mean there doing jasper and Rosalie's story?

Most likely, they will need to show flashbacks of what happened to them i'm guessing.

i think they will do flashbacks like they do when jacob is telling bella about the treaty in twilight but those stories don't happen till elcipse so we will have to wait and see ps this is gouing to sound really sad but new moon comes out in the uk in 2 months and seventeen days

yes. they are filming both Jasper and Rosalie's past.

Beginning of Eclipse filming, which was August 17th, they filmed Jasper and Maria, during the war. They are still filming his past as we speak. The other actors continue to have fight training and what not. :)

they proberly will