Upon their arrival, just take them to Medical Commission for medical check up. Do not forget to carry their picture and passport with you along with visa copy.
The medicle repor will be out in one week time. Collect the medical report after one week from Medical Commission and then go to Immigration directly and stamp another 5 months visa in their passport (maximu u will get 5 months more). You will be charged QRs. 200/- per person per month.