The McGuires do begin to get a bigger role in the third series - and they get some quite funny scenes.
Anyway - great news it's getting a fourth series, just hope we don't lose any more of the cast. I know that Kev, Lip and Veronica all have roles outside Shameless in the next few months - but I think most of them are just one-offs so they will hopefully be back.
Having said tha though it be interesting to see Kev and Veronica go and the neighbours from hell move in!