I will only focus on current track.
A selective coward?
Raman Bhalla silently agreed to take Shagun and Adi in his home. He once scolded Ishita for bringing Shagun in his home. But this time he was an willing participant. Some people will argue he did that for his son and Shagun was Adi's mother, so she had to tag along? Then Isn't Raman the mighty RKB? Can't he buy a house or at least lend it for them? They can again argue that Adi is a kid and since he is mentally disturbed he needs a family atmosphere. In that case he can buy or lend a neighboring apartment. Instead he preferred to live in the same house with his ex and current wife. Isn't he encouraging polygamy? Is this the same RKB who always beat creeps like Ashok and Param black and blue but can not stand for what is right? Is he become a selective coward that he can fight with creeps but can't distinguish between what is right or wrong? Will a husband with some self respect live with a wife who cheated him for years? Raman could easily ask Mihir to let Adi-Shagun in his house as they were happily living there for months. Instead, he acted like a coward and preferred to be a mute spectator.
Or a cunning fox?
Another possibility could be Raman secretly wishing all these to happen. That's why like previous times, he didn't raise question to Ishita for once why she kept them in their house for so long. He could not say that openly but Ishita somehow sensed that. He longed for a perfect family that would include Adi, Shagun and Ruhi in it. It is not a crime to have this kind of wish but while he is married to another woman, he must first get a divorce. If he is not secretly wishing the current state, why is not he objecting it? Is his love for Adi and Shagun overpowering his senses or he wishing this state to prolong as long as possible?
Shagun needs to stay in Bhalla house because she is financially insolvent, doesn't have any job. It's very easy for mighty RKB to solve all her problems. Raman Bhalla can easily give her a well paid job and even can provide her financial security. He did the same for Sarika while parting her away from Romi and when she got pregnant Raman wanted to bear all her expenses for the rest of her life. Then why can't he do the same for his son's mother, Shagun? Isn't it a double standard?
So many questions unanswered yet he prefers to remain as a spectator to enjoy the current situation to the fullest. He is enjoying the current situation because it will ultimately give him back what he really wants in his life--- his love Shagun and his children ghar ka chirag Adi and Ruhi.