Spoilers... The role of Kamal's wife is what ties the story to her place of work, Deep Research, which supplies the Cesium to the terrorists. So, from Nirupama's POV, it is MOC, for her to realize her ambition of becoming a scientist - Nuclear Oncologist specifically, and for Kamal, it is to gain access to the information stored by Deep Research. Yes, this could have been done even without Nirupama's character, but understand that the movie also has to cater to the local audience. As for Andrea, she is the link between Domestic Kamal and Shekar Kapur and Dawkins in her role as Kamal's student. This is what I understood from the movie.