Feeding posts from subsites to main site

Hi there,

i am trying to feed posts from my subsites onto my main sites in their respective categories as shown here:

http://cym.org.au

I cant seem to get this to work for me at the moment and was hoping you had some suggestions as to how to do this.

The theme allows me to add category boxes (as shown), is there a way I can could global categories, and as a result feed off these?