Can a Mage be Both Communion Slave *and* Master?

[Shovah32]

Only one of the group casts spells every round - that is normal. When any master in a communion casts a spell, other masters are not affected but no slaves may cast spells in that turn. If all mages are both slaves and masters, only the first will be able to cast, then the rest will be stopped by the slaves inability to cast after a master.
I can't remember if slaves can cast before a master(slaves scripted to be first in the casting order) but I have a feeling that they can't.