Maybe, with the customer's permission or assent in the T&C of the challenge, you could publish the account number and the amount of refund, in alphabetical order or something.
My thoughts : You guys are finding your feet as a broker. This 30 day challenge is a great marketing activity. Keep that up. But don't get involved in any extraneous activity, which can be quite taxing and counterproductive. Just concentrate on trading tools etc. till you at least have a critical mass. What would Fyers gain by analysing the performance, relative or individual, of the traders ? Won't add to the brokerage or turnover.