This sample BIRT report shows a way to make sure that ALL always shows in your cascading parameter drop downs for all levels when using an SQL dataSet.  Script is used in the beforeOpen of the second level parameter's dataSet to handle an "ALL" selection in the first parameter, and script is also used in the beforeOpen of the tableDS dataSet to handle when both cascading levels are "ALL" or when just one or neither is.

This report was designed in BIRT 3.7.0, but this idea should work in all versions.