dynamically choose a member in dimensional report

[BaldNomad]

I have a crosstab report based on a SQL Server Analysis Services 2005 cube.

My time dimension has two hierarchies: By Fiscal Week (Year, Week, Day) and By Fiscal Year (Year, Qtr, Month, Day).  I have a prompt where the user selects a single week, resulting in a data item called Selected Week that contains the member "W/E 11/08/09" for example.

How can I write an expression that returns a reference to November 2009 (I need a reference to this member in the By Fiscal Year hierarchy) based on this selected week? Of course it must be dynamic.  Specifically what I really need is an expression that would return the month (from By Fiscal Year) that is the same month as the first child member of the selected week.  This is because I need the month of the first day within that week (the child days of a week can span month boundaries).

I looked at the linkMember function but apparently that only works with Cognos cubes, not Microsoft.

Also, does anyone know of any good examples of REAL (i.e. DYNAMIC) reports against dimensional data sources in Report Studio?  Most of the examples are useless because they are static - in other words I don't want to have to go in and update all my reports every week to put in a new hard-coded week...all the time periods need to be RELATIVE to the one selected by the user.

Thanks for any help!