Labour related query

One of my client having factory at Silvassa (UT). Their existing workers (apprx 50) are wish to  work overtime 4 hrs a day and my client is also ready to pay double the salary for 4 hrs OT.
 
As per factory Act maximum allowable OT is 48 hrs in a quarter. Whereas 4 hrs per day OT comes to 104 hrs per month and 312 hrs per quarter.
 
My client query is that can they apply to local Labour office to get the permission for workmen to work over time 312 hrs per quarter ?
 
Is there any provision under law that Local Labour office (in Silvassa) permit to factory for extra over time if Employer and employees are jointly ready and sign the Agreement.
 
Please advice in the matter