Unfortunately not with Real Drums. The RD's and RT's are prerecorded audio tracks that Biab chops up according to your input on the chord grid. That alone is an amazing accomplishment but still limited. You can't fine tune an audio track like that. Unless there's a RD part that was recorded as hi hat only, you're stuck. Think of it like one of you're favorite commercial CD's. Imagine if you're question was about taking one of the tracks of that CD and changing the drums. Same thing.
What you can do is put the song into Real Band and create a 2 bar midi hi hat part and if you have a good quality midi synth use that. I have Jamstix and the drum kits sound just as good as the RD's but since all the hits are just samples triggered via midi I still don't get the full on live feel of a RD track but it works well for a case like this. I mix midi punches and fills with RD tracks all the time but you need a sequencer for that, not Biab.

Bob

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