Sandhya, Surrogate mother?

Maybe She was for Kunal? And later on Nirmala gave birth to Karan and after that all Ignored her?

I know this is stupid but what's what came in my mind after watching the flashbacks

Reasons to support my stance are:

1) Being surrogate mother of Kunal might be the reason she was in Chauhan family before Karan's birth

2) Reason why she flavours Kunal more than Karan

3) Nirmala is also more close to Karan than Kunal and Nirmala once said during MegNal wedding that to Sandhya that she's also like a mother to Kunal

4) Sandhya said she gave so much to the family so what can be more important than giving the family their heir (Kunal)

5) This could be why she's insecure o jealous of karan

P.S I know I might be wrong but still, that's what I feel that she was Kunal's surrogate mother

I think the relation is more to do with Nirmala. Sandhya is a VERY ambitious person and knows how to get things done - yet Nirmala who hesitates on every step due to her bg has literally got everything handed down to her on a plate. I believe there's some kind of power struggle in her which she is trying to climb and claim by keeping the rest dependant on her.

I hope they don't go the Bidaai way where the marriage proposal went for older sister but groom chose younger sister. I know Sandhya and Nirmala are not siblings but there us a deep connection. She may have come with Nirmala to see if she can achieve her goal but at first would've struggled and during this time she may have had to give up on many things. Hence her 'grudges'.

But what she is doing with Karan is pure evil. Karan may have had a condition which she has exasberated to keep everyone running to her whenever something happens to him as only she can 'care' and give him 'relief'. This is a powerful hold over the entire family as they all share a huge level of concern when it comes to him.