What a thought-provoking & interesting question. Well, I have a doubt is the child a girl or a boy?
If a boy, he would have Tejawat's mooch, unless and until he is a foreign returned dude and has a funny accent. He could be a long lost friend of Paro is what many speculate, but why have him related to PaRud? What if, he is back for revenge, for knowing how his bhai, Varun was shot and is infact a bigger threat than Tejawat himself and makes the BSD shiver, atleast for a moment.
If it's a girl, Rudra ji would be the least interested, as he is busy falling in love with his Shrimarti and I believe has no more energy left to give away maafi and accept family members, just like that. (She being a step sis)
If she is a threat, I am happy she would not in the least bit affect PaRud, but would shake their world if she marries Sumer, by hook ya crook. (A constant remainder of Mala's 15 saal ki absence)
Sorry abt the over-analysing and haphazard reply. I am sure all of you have wonderful and realistic takes on the same.