Even when there are multiple OBS structures associated with the Resource object, there is only one OBS Unit and corresponding Filter Mode available to add to the filter. This allows to only filter using one OBS at a time.
Is it possible to add more than one OBS Unit filter parameter?
Release : All Releases
Component : CA PPM STUDIO
There is not an option to add multiple OBS Unit parameters to the filter. However, the Power Filter option can be used instead to combine different OBS Unit criteria.