In general I'd look at using a Conditional Split to divide up your collated dataset by campaign. Though I haven't done so myself, there are plenty of articles on the Web about creating dynamic output filenames for Flat File Destinations using SSIS variables. Just google "ssis dynamic output filenames".

That should get you going. But if there's anything I've learned about using SSIS, there's usually more than one way to accomplish a given task.