PivotTable Olap Use Set in Where

In my MDX I can write a where that contains a set (ex futureDays).

So when I do a select i will only get the days in that set.

I can use this in excel too, but only in the column of row, not in the filter.

is there a way to achieve this.

basically I want to use the set as a selction on dates but not showing each date seperatly