brundlefly
I speculated in my first response that this probably wouldn't work. I just tried it and verified the 4/4 steps don't retain their timing when you change the steps/beat. They retain the step number so the 7th step in a 6-step pattern that was the downbeat on 2:01:000 is now at 2:03:000 in the 4-step pattern.
 
I still think just adding a 1-measure, 6-step pattern in another lane is the way to go. Or just work in the PRV where there are no limitations on note placement.

When you say another lane - do I open another Addictive Drums 2 on another track? Or would it be two midi tracks with on AD 2 synth? All I have done so far is have one midi track for AD 2 and I was not aware you could have another lane - like take lanes?

A track can have multiple lanes of MIDI (or audio) data running in parallel. Shift+T will show lanes on the focused track. Click the + button in T1 to add a new lane.
 
I'm not in front of my DAW now so not 100% sure about how to start a new SS clip in a specific lane, but I think if you make sure the new lane has focus, and click the Step Sequencer button in the AD2 properties window you'll get a new SS clip in the new lane.

brundlefly
A track can have multiple lanes of MIDI (or audio) data running in parallel. Shift+T will show lanes on the focused track. Click the + button in T1 to add a new lane.
 
I'm not in front of my DAW now so not 100% sure about how to start a new SS clip in a specific lane, but I think if you make sure the new lane has focus, and click the Step Sequencer button in the AD2 properties window you'll get a new SS clip in the new lane.

Yeah, I am not in front of my DAW either. As soon as I hit reply, I thought, Al you dummy, it's like take lanes. D'oh - Homer Simpson moment. Just make the take lane MIDI instead of audio. Got it!
Conquering triplets one step at a time. Ha! Ha!

Al

If you stack track lanes, don't forget to set this.  Otherwise you'll probably have problems with stacking the take lanes over top of each other.
Change Preferences > Customization > Editing Drag and Drop setting to "Blend Old and New"
 
I've been changing my drum tactics for a while now.  I go into AD and tweak the drum set the way I want with direct audio outs.  Back in track view, I'll create a Drum folder and insert AD direct out audio tracks for Kick, Snare, Tom1, Tom2, and so on.  I'll put effects, usually reverb & compressor, in the effects bin or prochannel for each if desired.  Then I'll put a midi track below that to trigger the AD drums.  I set my Drum Map so that when I open Step Sequencer and add drums to it, the drum names are retrieved from the drum map.  All that can be saved as a template for future use. 
 
Then, under the midi track I create a step sequencer clip as 4/4 or 6/8.  I add drums to the Sequencer until I have the kit pieces I want.  I sometimes save this as a SS Pattern so I can recall that setup.  Generally I like to do all the drums I can in one take lane, but occasionally I'll have triplets over top of a 4/4 pattern and I'll create a separate track lane with a new 6/8 SS clip.
 

craigr68
If you stack track lanes, don't forget to set this.  Otherwise you'll probably have problems with stacking the take lanes over top of each other.
Change Preferences > Customization > Editing Drag and Drop setting to "Blend Old and New"

Thanks craigr!

Will that preference change stay that way for just that project? Or will that be the default for any project I open until I change it back?

Also, when I have different take lanes like this example (for AD 2 and for purpose of triplets) do I need to comp the takes?
Just curious because I have not tried comping yet.

If I was at my DAW right now, I would just try it and see what happens.

The preference setting will be the default for any project until it's changed back.  I've only used comping to do multiple takes while on the fly recording.  With step sequencer you're not really doing that.  You're just selecting squares in the step sequencer with a mouse, so I don't see how that would apply.