Hi,
Sorry, I've been away for a little while and haven't been able to answer you on this.
My setup has the following custom post types: Groups (Ryhmät), Persons (Luottamushenkillöt) and an intermediary post type Membership (Jäsenyys). Membership is a child of both Groups and Persons. The setup is just like Bands, Appearances and Events in http://wp-types.com/documentation/user-guides/many-to-many-post-relationship/. I understand the language must be difficult for you and I'm sorry about that Image may be NSFW.
Clik here to view.
If I base the query on the intermediary post type Membership then I multiple search results for any Persons that have multiple Memberships matching the search criteria. That is, I guess, the major problem I'm trying to tackle here. You mentioned on July 14 that "the feature "Many-to-many filter for Views" is already in our to-do list "Toolset major features", our developers are working on it, but I am not sure when will be released." Is that feature part of the latest Views beta package?
Regards,
Ilkka