The plan presented by Seif would set up a new opposition leadership body, setting aside a number of seats for the snc.
"We've made it clear that the snc can no longer be viewed as the visible leader of the opposition," she said.
The snc emerged near the start of the uprising, in the summer of 2011.
The snc announced Sunday that rebels would be receiving funding from Gulf states.
Islamist rebels deride the snc as a puppet of Western and Gulf powers and say it is not representative of rebel fighters.
He says infighting between the Army of Islam and brigades affiliated with the snc has made Aleppo more vulnerable to Assad.
Many in the wider opposition have remained skeptical that the snc is willing to share its leadership role.
One snc member, Kamal Lebvani, acknowledged this, saying, “The fighters are the ones who decide things, not us.”
Last month, U.S. Secretary of State Hillary Rodham Clinton sounded what many considered to be the death knell for the snc.
In the end, though, the snc's perception problem only worsened.