Dimension security : role, visualtotals and co

Hi all,

I searched into the forum but i did not find any solution on my problem, so here I wrote !

I have a dimension "group" with the "group hierarchy" which has 4 levels.

I would like to know if it's possible to enable visual totals only for 3 levels and get the grand total without filter for the first level ?

Example :                  

Level 1    500 (not filtered)

Level 2    10 (filtered)

Level 3    10 (filtered)  --- at this level I have implemented a dimension data security for the role, with this syntax :

                                                   EXISTS([Group].[Name].Children,

                                                             {StrToMember("[Portal User].[USER NAME].&["+username()+"]")}, "Factless Security Access")

Level 4     5 (filtered)

The level 1 represent the aggregation of all my group and it's important for user to get the information in order for them to benchmark their values to the grand total.

Any help would behighly appreciated !

Thanks