Filter All dimension members based on Factory while browsing

Hi All,

A cube contains data for All factories.There are 12 dimensions each contain factory specfic members.

Now the requirement is as below:

• As a standard the cube should open for the users factory only.
• When the user needs to see other factories data there should be an easy way to select the affiliate data from other affiliates. 

What are the best way of doing so?

Note:We have some constraint also:

• Cannot split the Cubes for each factory.
• There are 20 Factories and dimension security for hidding members are also not feasible.

Please suggest some options that can be done to achieve the requiremnt.

Thanks, Tanmoy Santra