Surrender of duplicate din

You have to surrender DIN which has not been used by your client in this case by making an application to RD in form RD-1. Here is the solution for your queries 

1) Please specify CIN of company in which your clinet is Director, if he/she is Director in 2 or more companies then you can specify CIN of any of such company.

2) You have to attach an Application to RD for surrender of DIN in this attachment, I have attached the format of same.

3) You have to attach a Board Resolution of a company whos CIN you have specified in the form, format has been attached.

4) Yes, you have to attach DIR-5 as an optional attachment along with an Application to Regional Director.

Hope this might help you.