I thought Jason Herbison's comment about not having room in the current cast for a love interest for the Brennan sister was referring to the possibility of bringing her in as a permanent character. Since romantic drama makes up much of the soap's output, it's bound to be important to him to have a character available as a romantic interest for Mark's sister (if he were to cast her). I agree there's no need for it, but that's not how the soap works. Neighbours is nearly all about small domestic and interpersonal drama, mainly of the domestic kind.
I was actually quite surprised he said they wanted viewers' sympathy to jump back and fore between Brad/Lauren and Terese - for the opposite reason to some of you. Terese was written for a long time as being so unreasonable that I thought all the writers' sympathy was with the lovers (who they appear to have convinced themselves are soulmates).
We know from the endless arguments on this board that some viewers did indeed sympathise with Brad and Lauren!
