2nd and later RingMaster's should be stacked with a MB. You MUST bring the RM up BEFORE starting a MB, then finish him while in multiball.
The Juggler Muliball (left orbit) is the most valuable and is only 6 shots
If you get 2 or more MB's stacked, always shoot the left ramp within a few seconds of draining down to 1 ball, to collect extra jackpots.