Eh, that doesn't work out, Cass had basically cut herself loose from the rest of the Clan at that point. Well except for that one brief unfriendly team-up with Tim, I guess. Standard War Games fallout. Not that Cass had much to do with Babs post-Puckett anyway, even prior to that nonsense...
I think Eddie went straight before War Games (it had to be around then, since he's still a black hat when the Cluemaster dies), so there may be a slim margin there where Steph could have found out and told Cass, but that relies on Bruce having told Steph anything important, and as we know, that's even less likely than him sharing info with Cass.