A lot more info about subs on the Genelec site in the actual sub product page
https://www.genelec.com/7350a#section-downloads
I don't know that either, but I doubt this is not the case. I mean these guys install professional installations with multiple subs all the time for famous people. I would expect this is a standard feature in this environment just for time savings alone.
miniDSP SHD is not and will not support Dirac sub management. That was confirmed on their forums some time ago. It would be really useful even with one sub output (automatic low/high pass, phase correction along with frequency response correction is really consumer friendly).
E: IMHO GLM has no competition at this time. Genelec system is expensive but you are getting the best there is.