Hi,
Just to make sure, we are talking about the same… You did the pattern in the Beat Designer, and as a tone generator, you are using Groove Agent VSTi, right?
So, open the Beat Designer. Find the “virtual Keyboard” on it. Click the light-grey key (where is your pattern stored), and drag-and-drop it to the Instrument track, where your Groove Agent is. Done.
Or, you don’t need to do this, and you can just create another pattern in the Beat Designer, which will be stored on the other key, and then just trigger these patterns by sending corresponding MIDI notes from the MIDI track. This way, you can trigger up to 48 patterns (12 notes in a octave, times 4 octaves).