I talked to Lauren Faust over skype this weekend and asked her what the contingency was if they brought in Rainbow Dashes Parents and she had tolled me her dad was supposed to be more subtle and self controlled as a person, and her mom was going to be Firefly. Just thought I would drop what I heard from the Horses mouth.
FYI This event occurred at the Kansas City film festival when she couldn't show because she was sick. She skyped all the fans in the back room before the film started.
From the looks of things the name of Rainbow Dash's dad been put on Wiki, not sure if someone just did it or it the name that going to stick, thought I just share this information to ya.
This wikia link shows the list of pony names and from the look of it... the name put up on this site is Rainbow Blitz but I don't think that would work since Rainbow Blitz is the name of Rainbow Dash's opposite gender for appearance for some time now.