How do I create calculated sets, for example for ABC groupings?

This might be helpful if it does not work for you.

You can change the order that they have in the calculate script within the two groups, but you cannot make a calculated member appear after the script commands. The only way would be to create the measure as a script command as well:

CREATE MEMBER CURRENTCUBE.[Measures].[ABC Group] AS iif( IsEmpty( [Measures].[Measure for ABC] ), null,

iif( Intersect( [A], [Items].[Item].CurrentMember ).Count > 0, 'A',

iif( Intersect( [B], [Items].[Item].CurrentMember ).Count > 0, 'B', 'C' ) ) ), FORMAT_STRING = "#,#", VISIBLE = 1;