I rather sense that,...
When Upen was outside, his mother must have liked KAR a lot and had advised him to bring her home to London after the show, and if she likes our family and way of living, she will be herself happy to be a part of our family.
More to it, I guess that, UP also must have met KAR's mom and that's how he knew that her mother also loves him a lot and she has some issue with that BF Choksi, and UP is told by her ,.. that if you can please her then she can leave that choksi guy and it will be good in all of ours benefits.
Could not it be like this ?