I think they are definitely related! in the precap apparently they were shown hugging--- who hugs random strangers! and when the girl said "main agaye" armaan turned around and was genuinely happy! it wasnt the flirting type of look nor was he checking her out. he was really happy to see her and hugged her. that could only mean two things that she is either his cousin which is likely since she is from punjab sanjeevani and he is punjabi or that they are family friends. im thinking cousins is more likely!
in any case i dont think that she will get romantically involved with Armaan and i think that she will be the person that Armaan can confide in because he doesnt have anyone to tell his secrets to. the poor guy cant tell anyone he loves Ridz and it must be eating at him.
So yea im sure they know each other from before-- just not sure how exactly!