Originally posted by: Animagus_Shiri
A girl, who want to get married to her long time boyfriend, marries her brother-in-law instead. The reason being the man's family's insistence on getting him married a second time due to his first wife's inability to conceive. The wife wishes only her sister to become her husband's second wife. When the couple fall in love with each other, they find out that both the sisters are pregnant.
Ans- Zaara

Year: 2006-2009
SaharaOne
I am also giving points to

(Because it started on Dec 2001, it was on air in 2002)
Year: 2001-2002
DD Metro, later on Star Plus
Even though the girls were cousins in the show, they were more like real sisters. And because many people gave this answer 😆