I always knew them as SANE. My guess is Freeze glommed onto old SANE mailing lists to get up and running. Freeze came in the early 80s and was trying to stop us from basing nuclear missiles in Europe. Am I right about this?
Freeze was supported by a lot of former Mobe and Moratorium activists with local/state grassroots organizations, so I'd guess they picked up their mailing lists in the process. They were formally distinct from SANE but they joined forces.
Heading towards bed soon here, so have a good one!