Entry VIisa for British couple (Mumbai)

Hi all. as our move to Mumbai gets ever nore likely I just wanted to see if anyone knew if my partner and I need to be married for a entry visa? He will be working for an Indian company so we are looking to stay for 3 years.min. we have two kids but are not married. cant see on the vida website anything about that as it seems to assume marriage.
Any thoughts or advice welcome
Thanks