May be she overheard what Nanhi said in Mohan's house about her returning to that house from sasural. May be she saw the three of them hugging because only after they break the hug, she comes and tells Mohan that Addu has opened his laptop. And the that evening she shows him the pic she took of MM together. And then talked of their marriage.
Also if you observe in the scene where Mohan complains about Nanhi's dress, you will find Rj right behinds thrm dancing. Don't tell me she is blind to not see three of them almost falling on each other and having a secret talk.
Then after engagement. She was happily opening gifts. Megha comes there with food and Mohan gets up and leaves. Megha follows him. She must have noticed it. Thats why she could enter exactly at the right moment to tell Megha that Mohan is only acting. He already had two plates. Then also without any complaints, she left.
Next comes yesterday dance rehearsal. MM were in that for quite some time before Rj spoke up. Could it be that she was standing right therr and watching. When she saw that Mohan couldn't find any excuse for dancing with Megha, she cutely made up an excuse for them. And then, reminded Mohan about the proposal.
Looking at all this, I feel Rj knows about MM. And like her papu is playing with Munna to confess addu, she is playing thr same game with MM.
What do you think of this? Share your views by commenting below.