I suppose while we're taking about creating canon, we ought to work out exactly how much of each canon we're allowed to shape.  The DCU, after all, has tons of legacy characters and spin-offs and whatnot, so it may behoove us to clarify the rules around, say, if someone wants to have Wally West be the Flash first, or someone wants to play Damian as Robin before Dick Grayson shows up, etc.