Shortly after the Rising Phoenix Clan's leader informed the Ten Royal Phoenix Clans of the gathering, the others promptly contacted the Celestial Emperor to report the situation, since failing to do so might have been seen as acting behind his back.
Naturally, the Rising Phoenix Clan had done the same. That said, the Royal Phoenix Clans had contacted the Celestial Emperor largely as a formality, and few of them truly regarded the matter as treacherous.
When the Celestial Emperor learned of the existence of a second Primordial Phoenix, he was just as surprised and intrigued as the Royal Phoenix Clans. Thus, he suggested that everyone take part in the gathering. Since seven of the ten had already agreed to participate, he was mostly speaking to the three who initially declined.
"Before we even begin, I would like to confirm something." Another phoenix suddenly spoke out loud. "To not waste anyone's time, I want to see for myself the evidence that you are a Primordial Phoenix."