I feel CV's may during the course of this track may initially try to take the viewers for a ride by actually making MK look like Sultan's father.
The way Radhaji is strangely behaving are sign of this impending move to give RK a jhatka and create lots of drama and tension.
After a while, when all the drama is over, some twist or surprise may come up to eventually show and clear the air that the two are not related. Bcos the CVs have left too many loopholes deliberately which they can exploit later on to end the track.
There is definitely some bigger story to Meera's than just what meets the eye, the present source of information for MK's betrayal are just Rashid and Meera . These are unreliable for obvious reasons. Radhaji too might end up beleiving the story as she is aware of MK's colorful past.
But I am sure the CVs will eventually produce a reliable source in the form of a person or object to prove MK never fathered Sultan by the end of this track after all the tamasha is over. We will then get to see Sultan leaving RK Mansion with bag and baggage and with his not so loony Mom by then for good.