You are not supposed to leave any cell blank in any form. If you leave it bank and sign the form, and later on someone fills the cell with is name (!), then you cannot challenge (or at least you will be dragged to unnecessarily legal battle) that you had left the cell bank and there was some illegal interference. Therefore, you may ask him to fill the name of his immediate family members and when he acquires a family let him change the nomination by giving another nomination form. Normally when an unmarried person joins he would be nominating his father or mother and in the Pension part he will not write anybody as family members but will write the name of father/mother as persons eligible to get the benefits in case he dies without leaving a family, and after marriage he will submit another form 2 with name of spouse as his nominee under PF and pension schemes. Also please note that under Pension scheme only spouse and children are family members who are eligible to get family pension in the event of death of the member. Under Pension scheme there is nomination only if the member has no family. That is why the PF form (form 2) is Nomination cum Declaration form, ie, Nomination under PF scheme and Declaration of family members or nomination if there is no family under Pension Scheme.
Madhu.T.K