I don't know if there is a step-father. Hawk obviously has a mother and you are right that she has only been introduced in order to show her deeply pregnant and to provide Hawk with a dilemma.
This is the problem I have with this program...TOO MANY CHARACTERS! It is a failure of the writer, because it seems like every time there is a twist in the plot, new characters are introduced.
To some extent a complex story must involve many characters and we have limited time to get to know them. But to some extent it is a failure in writing to introduce a character just to tug at heartstrings or to move a plot point.
I like that TV is trying to do some more involved stories. Formulaic sitcoms and cop dramas get old. I like to thank NBC for trying to do something different. It's not the best show ever, but it is interesting enough to keep me watching through its 6 episodes. Where they go from there remains to be seen.
SD
I will keep watching this as well, simply because although it is hard to follow, it is interesting, which can't be said about much on the networks.