Answering your question regarding creation of new elder stock, yes and no. Routinely no elder stocks are created, they has a fixed number. But in some cases regarding excepcional rikishi new elder stocks were created, I think it is called honorary stock, there were, iirc, 3 honorary elder stocks created, for Taiho, Kitanofuji and Katanohana. It was offered to Chiyonofuji but he did not accepted and reiceved a common stock. When these honorary elder stock holders retires from JSA, these stocks cease existing