Complex sentence: Is Sukhi's wife and Ranbir and Vicky's sister, she has a mind of a child and Sukhi and Kamla misuse this and get her married to Sukhi.
Split into simpler sentences: Is Sukhi's wife and Ranbir and Vicky's sister. She has a mind of a child and Sukhi and Kamla misuse this and get her married to Sukhi.