The other popular multi-sub application I am aware of is @andyc56 's MSO, multi-sub optimizer, and I am thinking of trying it and comparing it to SFM. Or just using MSO if SFM turns out to be a stretch. MSO is free, depends upon REW (as does SFM for the do-it-yourselfer), and Dr. Andy is available to consult.
I am planning to try to use that as well when I put the minidsp 2x10 in to take care of the Subs.
I'll be interested in what you find.
https://www.andyc.diy-audio-engineering.org/mso/html/index.html