Funny you mention that Pulse, as my missus was at the same venue for the same position 2 weeks ago.
She only had 2 other applicants of the supposed 8 rock up, so hopefully the same thing will occur for you, the process also only lasted about 4 hours instead of the 5 they had stated. Be prepared for "official actors" to pose as both parents and the higher ups in staged scenarios.

STL had some great points, unlike most jobs I think a group interview for DoCS jobs is a good idea, it's a real people person job, so being able to handle the rude, intolerant and downright stupid at the group interviews should allow the markers to see if you can handle the same kind of things once you are on the job.

Goodluck