At this point of time, miniDSP unfortunately does not support Dirac Live Bass Control (DLBC). Also important to understand is that DLBC is expecting a main speaker pair to align the subs and this set of non-sub speakers to be under control/processing of the miniDSP processor. DLBC will align that main speaker pair in the crossover region for all subs. In other words, you can get clarification on the most typical question we get: Why don't you get us a MultiSUB processor with DLBC for subs only?... It's simply not possible as it would require all your other speakers to be processed by Dirac.
Last but not least, DLBC is software/firmware update that isn't limited by a specific chipset so the lack of support may change in the future but we can't share much more as per our company policy.
In the meantime you can easily handle multiple subs as per the following app notes:
Feel free to contact us if you further questions.