Gift to father and mother in law

I would like to gift Rs. 10/- lacs each to my father in law and mother in law who have no source of income. By doing this they will invest the amount in bank fixed deposits and will earn income thereform. Since their yearly interest amount is below taxable limit no income tax will be payable by them. My query is do I need to club their income in my income? If not then do I have to execute some document so the IT autorities can not question gift. Please advice.