Tulsi trying to save karan(not her biological son),mihir trying to save karan and harsh(not his biological son).
mihir tensed abt karan,finds out harsh is the killer.so decides to save both his sons.destroya evidences against harsh in a way that tulsi doubts mihir.
now mihir refuses his crime as he wants no one to doubt that he is doing a sacrifice.later mihir would prove that he is the killer.then harh would confess or tulsi will find out that harsh is the killer.
every one(tanya) apologises to mihir.and maan singh says to mihir -ooh yes u were right ,aap ko koi maath nahi de saktha.what a family -an ideal son ,and ideal papa and an ideal mom.
then tulsi happy and proud to be Mrs.mihir virani .
SO IT IS IN FASHION THAT ,ALL BALAJI CHARACTERS DO ANYTHING TO SAVE THEIR NON BIOLOGICAL CHILDREN.