I converted my ATPL(H) to Indian ATPL(H) by doing 1 exam at Bombay airport. The first time I went to India was for a 4 week tour and for that I just had an interview in Delhi to establish I knew something about the monsoon season. However when my company wanted me to go again, I had to do the exam. This is to fly an Indian registered aircraft. When the aircraft was on the Canadian register, I used my Canadian license. Don't think you can do that any more.