...the following reasons.
1. I don't want to see Santo being portrayed as mother to DM's kids, especially kids who are older than her. It is grave injustice that she has been married off to a man who is old enough to be her father. It would be worse to see her actually being addressed as 'Ma' and treated as one by his children, three of whom are older than her. While I can accept a husband-wife relationship gradually developing between DM-Santo, provided they show it as a mature relationship and not one that is based on physical attraction, I don't think I can ever palate Hiten treating Santo as his mom anytime in future, even if that future is remote.
2.Hiten and Khemi will make an interesting pair. Apart from being an attractive couple, the manner in which their personalities will be made to gell would make interesting viewing. After all what is more attractive to watch than the development of a hate to love relationship?
3.It will bring in greater complexities into DM-Santo relationship which will be interesting to view. For instance if DM comes to know of this relationship he can act in two ways:
a. He may be against the match because it makes his own relationship with Santo more complicated given the fact that Khemi is his sister-in-law (although right now they are both chokris to him). So how can he accept his sister-in-law as his daughter-in-law? This question will arise in his mind. But if he does not recognise Santo as his wife, such a question should not arise in the first place. This may lead to his questioning what is Santo to him and maybe in the process he will accept, however grudgingly that she is indeed his wife and he needs to give her that place before he goes around questioning Hiten's intentions to marry Khemi.
b. He may accept their relationship since his relationship with his son is already strained and he would not want to strain it further by coming in the way of his son's happiness. This may lead him to try finding ways to get out of the relationship he has with Santo.
This feeling may be reinforced if he finds out that Duggu was in love (and perhaps still in love with his wife). This may make him ponder over how his decision to marry Santo (for his own gains) has affected her life. Right now I dont see any sense of remorse in him for using Santo for furthering his own gains. He keeps telling her she is no relation of his but by being tied to him in marriage, her life has come to a stand still. He still has not realised that as yet. He is no better than his sister. While Moti Bein openly states that Santo is not fit enough to be treated as a human as she comes from a low caste, he has so far done nothing to accord a treatment which would befit a fellow human being. But for Meghna-Rasik's presence Santo would have still remained in that dungeon of a store room. So silently it seems he too accepts Santo's place in that store room.
The story will get more interesting if in the meantime Kaddu-Duggu wedding preparations go on and on the wedding day he comes to know Duggu's love for his wife. Knowledge of Duggu's love for Santo and Hiten's love for Khemi (if it materialises) will be his wake up call. If he tries to unite Santo with Duggu for her own happiness and for his son's happiness (because then there would be no social restriction for Hiten-Khemi union as Santo would no longer be his wife) , then he will definitely rise in my eyes for he would put someone else's interest above his own.
What will Santo do in this case? As I expect Hiten-Khemi relationship to develop slowly, by then Santo would have fallen for DM. She can then let DM know that she cannot accept any other man other than him as her husband. This can then be the trigger point of confession of love between DM and Santo.
What will then become of Hiten and Khemi? At this point they can reveal that Santo and Khemi are not really blood sisters.
So that would take care of the social taboo as well. By maintaining the suspense of the real relationship between the two sisters, the makers can make this Hiten-Khemi relationship (with parallel development of the Santo-DM relationship and the marriage preparations of Kaddu-Duggu) an engrossing track.
Dont know whether I was able to convey my thoughts on this complex issue clearly. Would like to know your take on this.