Custom Mod for Templatic Geo Places Theme

I have a Geo Places theme from templatic oh which allow user to add post and add category in front-end. However, the way it output the category is sorted alphabetically only (mixing parent & child category together) I need to reoganize that out put in a proper manner (refer below). [ ] Parent A [ ] Child A1 [ ] Child A2 [ ] Child A3 [ ] Child A4 [ ] Parent B [ ] Child B1 [ ] Child B2 [ ] Parent C [ ] Child C1 [ ] Child C2 [ ] Child C3 [ ] Child C4 [ ] Child C5 [ ] Parent D [ ] Child D1 [ ] Child D2 [ ] Child D3 Where the parent category should be non selectable. Whenever a child category is selected, it should automatically select the parent category. Do contact me more in PM.