I am in almost the same exact situation as you. Grew up in a Steeler family before the Cards moved to AZ. My father's side of the family is from the greater Pittsburgh area. My sisters are still Steeler fans. I always liked them, but they are my distant #2 team now.Go Steelers!
They are my 2nd favorite team (distant 2nd behind the Cards) and more importantly, my Dad is a huge Steelers fan and Cards hater. If we luck out some more and the Iggles inexplicably lose to us, and we somehow win over the much superior Steelers, that would be awesome!