Thank you for responding, although you didn't answer any of my questions 
If I may suggest: gather all the evidence you have and post them in the correct chronological order. This will make it easier for us to understand what actually happened.
I'm asking this because your recent posts made be a bit confused: you rejected his withdrawal request, asked him for kyc, his sister account was banned a day before, you realized both accounts belong to the same person, a third account may be connected too!

I believe the strongest evidence you have here is that both accounts provided the same address. But I'm afraid you will need a trusted third party to verify this information.