Hi Carsten,
You have register all system to your central SLD, better would be you use LOCAL SLD of SOlution Manager or separate instance of SLD.
Then this SLD will be linked to LMDB with a lower rank in SOLMAN_SETUP.
Then you create techincal and product system in LMDB, putter those systems in a SOLUTION.
and when all is done, you go for basis setup to manages system configuration.
Refer below link.
Landscape Management Database (LMDB) – FAQ
Maintenance of Product in the System Landscape - SAP Solution Manager Setup - SCN Wiki
http://wiki.scn.sap.com/wiki/display/SMSETUP/Home
Regards,
Divyanshu