The girl Marti met at the record store is her half-sister.Not just because she's played by Aly Michalka's real life sister AJ but because she had a definite reaction when Marti said who she was looking for. Also why did "Pops" profess not to know who she was talking about if he's such an authority? He at least knows the relationship or maybe even is their father.
The channel to pick up from where the 1st season ended will be ABC Family.Think about it: The CW decided not to renew it. 7th Heaven aired previously on both ABC Family (in Reruns) and in The WB (its original channel). There's even a tweet that hopes that channel will pick it up. And with two Disney graduates in the show (Three if you count Power Rangers: Dino Thunder's Emma Lahana), there's a big chance it'll continue there.