Hello Alfons,
the Universe doesn't have the same concept so the only option right now that you have with the Universe as a data source is - depending on what you looking for - to have multiple sources.
also keep in mind that for the BEx query there is also the option in the Initial View to configure if you want to see the master data, cube data, posted nodes - which impacts the getMember as well.
regards
Ingo Hilgefort