I too have a feeling Anurag's chacha-chachi is somehow related to Bajaj's past . 2 points that I have thought over in details are :
1) Everyone including the Sharmas (except Rajesh Sharma who is dead now) and the Basus (except Mohini Basu and Anurag's chacha) know Moloy Basu post his marriage with Mohini Basu. Only Mohini Basu, Prosenjit Basu (Anurag's chacha) and Rajesh Sharma know the real Moloy Basu closely from before marriage. Since Rishabh Bajaj's enmity is probably with the Moloy Basu from before marriage with Mohini Basu, I feel it's only Prosenjit Basu and Mohini Basu who can really know some secrets. Another person who knew Moloy Basu closely from the past is his best friend Rajesh Sharma, since Moloy Basu had himself admitted that it was Rajesh who stayed with him "through thick and thin" while he was laying the foundations of Basu Publications. But alas, Rajesh Sharma is now dead. Had he been alive,perhaps he would have been able to shed some light on Moloy's past. Now 2 persons are left who can actually reveal some secrets about Moloy's past - his present wife and his brother. Based on what type of person Mohini Basu has been shown till date, I don't think she will open her mouth even if she knows something. Thus, Prosenjit Basu is only left who can actually help in understanding how Moloy Basu was in the past before his marriage to Mohini. So, I too agree the writers have purposefully brought in Anurag's chacha-chachi now, as they will have a central role in revealing the secret of Moloy Basu's past, specially Prosenjit.👍🏼
2) Also, I am very curious to know what actually caused the rift between Prosenjit Basu's family and Moloy Basu's family since it has been mentioned in the last 1-2 episodes that something had happened in the past which caused Moloy Basu's family to completely cut-off all relations with his brother's family. Mohini Basu has been shown to forgive them and say " We didn't like what you had done earlier and so didn't invite you to Anurag's wedding. But now Moloy needs now." Is the thing which happened in the past somehow related to Bajaj ??? 😳😳
I was frankly surprised they didn't know Prosenjit recognizing Bajaj. I mean, by my theory, Bajaj is his nephew. Unless he was a secret kid, Prosenjit would know him.