Sayyed,
If you employ five contractors and of which two contractors have less than 20 workers then you cannot insist those two to deduct PF. From his view he is right. He cannot apply for the PF code in anticipation.
Similarly at the time of engaing a contractor, please mention all statutories to be followed. Any liability not complied by the contractor comes on the Principal employer. Many a time, Contract Labour Act is not strictly followed anywhere and principal employer is also not serious about this. The remedy is that you have to deduct and remit on behalf of them.
Again there is a headache. His staff who turned up this month may or may not trunup next month. You cannot collectively remit as group PF. So individual member registration and paper work is more. Anways, approach a consultant for more clarity, doesn't matter if it costs the company.
Regards,
Chandru