I tend to agree about Sheriam and Verin. Velina may have been a Supreme council member since she was afraid to be seen plotting with Elaida and she probably wouldn't have feared someone if they were simply a member of her heart, but who knows? The other are more speculative. I do think that one of the Supreme council was among the group sent with Liandrin too.

One aspect of the purge that might be noted is that Egwene never thinks to hrself (at least so far) about finding any of the Supreme Council among those executed. That would indicate that Alviarin may have succeeded in contacting those women first and escaping with them. That would neatly exclude Sheriam and Verin who were already dead but would also imply that there were none of the Council among the rebels.