Mamakin - in answer to your questions
Toadie's odious little chum (disclaimer - I would never describe a child as "odious" in rl ) Callum is, iirc, the grandson of Steph's cleaning lady (or similar).
Storyline was that Toadie returned from East Timor planning to adopt a child he met over there. Adoption fell through and he was upset.
To cheer Toadie up, Steph babysat Callum and engineered for Toadie to meet him so he would be distracted from the non-adoption sadness by becoming a role model/mentor type chap for Callum who is "troubled" (can't remember reason for this)
Toadie at first is having none of this, but then Callum starts to display true obnoxiousness - melting Toadie's heart and putting him straight into "mentor" mode.
Callum's grandmother then becomes ill, so Toadie (despite only knowing him for all of 5 minutes) is now looking after him.
Cue lots of heartwarming scenes showing Toadie "getting through to him" through the mediums of play-wrestling and splurting the shed with paint guns etc, and without recourse to any kind of telling off for general theiving and smart-mouthedness whatsoever.