Kavita and Kaveri's motive

Can anyone here clear my doubts? Actually i just want to know what really kaveri needs, past 5 years she separated sanskar and kavita, then she locked kavita in hospital even after she recovered from coma, then for money she blackmailed dp, if kaveri don't want sanskar kavita to become together means why she made a cruel plan by murdering urvashi to make sanskar kavita marriage, what is the need for doing a murder if she would have allowed them to marry before 5 years itself, what is the need to make her own daughter locked in hospital?