I don't have 1.2 installed on this computer right now, so I can't give you the menu commands, but you can point to a central location for step files, and the links between PADS Decals and STEP models are kept in a database that is used on all designs. You don't have to reconnect decals and models for each board.
Once you are in Layout, the xDx Central library isn't used, the decal information is stored in PADS libraries
