I am trying to create custom group date dimensions. For example I have a date period that starts 12/31/2012 ends 12/31/2013. I have several more date periods that have start dates within that start and end date. I want to group these dates together and identify them as falling under the start date of 12/31/2012. Any ideas what the best way of doing this is? Would it be a calculated field or a date parameter?