Setting aside exparte

If the respondents/defendants are set exparte, an application under the relevant provisions to set aside the exparte order has to be moved by the parties who are set exparte alone. It seems you are new/3rd party interested to join in this application. IMO its not possible as you are not a party to the original application/suit. First let the set aside application get disposed of and the parties who are set exparte be allowed to contest the proceeding. Thereafter you can get impleaded in the proceedings. 

Hope this helps...