DD issued by a person who later dies another person claiming that DD.

N is indebted to A for a sum. N procures D.D from his son in law in the name of A, who is also engaged in similar business like N. N issues the D.D. to A. A pass on the money receipt in the name of N. Later N dies. Son in law of N then approaches A and demands the amount of D.D. saying the amount was kept as deposit with A by him and files a suit for recovery against A. How A will defend the suit. Any citation on the situation.