Indians who married foreigners, how did you do it ?

My cousin is dating a girl of Indian origin who lives in UK, she holds a Singapore passport and has no connection to India (Her great grandparents moved from India to Singapore during British period). They are planning to get married and I told them they have to get married under special marriage act in India. My cousin said he can get married in UK and inform the Indian consulate that should be enough. Can you get married aboard and register your marriage in India ? Did you have to marry again in India ? What’s the easiest way for Indian government to recognise your foreign partner as a wife/husband ?