Hey Elmo, Yes it is. I was extending the Visit Visa for my family after 180 days. Your Extension Request will be approved only before a week of Visa Expiry after which you can pay the money and extend for only 30 days. It will keep going that way until you leave the country. If the Visa holder leave the country, the VISA will be devalidated and you have to raise a new visit visa for them which is obviously not yet opened.

Best Regards,
Riyaz