finding a group rate with a TA

[Skippy24]

For my families last trip we were able to get on someones group rate through a TA. So I was wondering if there is a way to find out which TA have a group rate going on during my month of travel or woud I just have to contact a bunch of them for quotes? I know it's a long shot, but if you don't ask you ever know right. Thanks for any help on this.