Self cheque

Consult a lawyer personally. show him the documents

If what you have written is true, your relative cannot claim the amount. If he goes to court, you submit before the court the facts as you have stated here. If a person gives a cheque across counter in a bank, the bank will not give cash unless the person presenting the cheque signs on the back of the cheque. Your relative will have to prove as to purpose for which he gave you the amount.