Fake Gst registration

Sir 

I have a client whose pan card was hacked and with this pan card there where two business setup established at Delhi and Rajasthan but both business setup were inactive in Gstand had transaction approx 50 lakh. can I apply for gst registration for the client and file income tax as usual or should I go to dept. And inform them about those fake business setup? Kindly guide me how to over come this problem?