Ours is an engineering company and we have given entire manufacturing activity on contract for three different contractor for three different operation. They have employed people less than 20 each. We have employed managerial staff and paying ESI and PF. Contractors are covering ESI for all their workers. We would like to know whether we have to bring the contract employees also into purview of PF. If yes, whether we have to insist the contractor to register themself with PF even though their strength is within 20.