While they are not specifically shown on the org chart, I assume they exist under the National Operations and Standards branch, Air Navigation, Airspace & Aerodromes section.
Last I dealt with the OAR - albeit some years ago - there were then only 4 staff. A manager, an airspace specialist (both ex RAAF ATC), and two others non ATC/ATS handling safety and coordination matters. There was also a RAAF person dealing with military airspace matters.
Things may have changed since. There was somewhat wider ATC/ATS experience elsewhere in the branch they were in.
I don't know that at that stage they saw themselves as airspace designers or initiators/originators of airspace changes. The fact that (at least back then) they didn't have the staff, experience or electronic airspace and air route design tools tends to suggest that they saw themselves at a higher level with oversight, and changes would be originated by others in the industry.
Again, things may have changed since I dealt with them.