Complex sentence: In the German football league system, however, reserve teams are not allowed to get promoted above the level of third division and from 2008-09 will not be allowed to play in the cup competition to serve the non-reserve team's interests.
Split into simpler sentences: In the German football league system, however, reserve teams are not allowed to be promoted above the 3. Liga and from 2008-09 will not be allowed to play in the cup competition to serve the non-reserve team's interests.