Sentence:  During this time I came to know about tubectomy from my <WSD>co-sister</WSD> and also from the female health worker. This time both my husband and father-in-law refused [me the surgery] on the ground that I was the eldest daughter-in-law and a responsible person for the whole family. 
Meaning of the word marked with <WSD> tags:  One's spouse's sibling's wife.