Originally posted by: Nafs_Sweetheart
Half brother Mallu, step brother is when neither of them share biological parents but only share parents after they marry each other after they leave their spouses. Here RK and Sultan share one parent that makes them half brothers. Sikky and RK are step brothers because they don't share parents biologically but one parent each have married now.
Because Mohan Kundra married Radhaji without divorcing Meeraji that makes their offspring illegitimate. That's why RK is Naajayiz person.
There is no marriage registration, just one old photograph and a drunk in name of witness, which as per Indian law is uncountable as solid proofs. So, basically MK's first marriage is null and void legally. So, RK is not illegitimate.