Taxation on Gift to son or daughter in law

I intend to gift a monetary sum to my son/daughter-in-law as a part of inheritance. I understand that gifts of any quantum between close relatives are non-taxable for the recipient however would their overall tax liability on the subsequent interest earned on this corpus (or subsequent investments) be lower if I gift it directly to my daughter-in-law (employed however fits currently in non-taxable slab) vis a vis my son (30% tax bracket). Or is it all the same, regardless of who receives the money, from a taxation perspective due to clubbing of income or any other provisions applicable on the income generated henceforth, given the relationship. Secondly, what documentation is needed for the eventual recipient to ward off any unnecessary scrutiny from IT Dept.