There only needs to be 1 asm. Assemble the parts using the correct connections and not worrying about the offsets. Go into Mechanism and create the drives. Then use the Profile tab to set up starting conditions and any limits on the motion as well as the zeros for this joint. You can use the specify references to set up things such as 2 planes mating.
In the profile tab press the icon in the specification area.
In the profile tab press the icon in the specification area.