2. Noun. Daughter-in-law of someone's sister. ¹
3. Noun. Daughter-in-law of someone's brother-in-law. ¹
4. Noun. Daughter-in-law of someone's sister-in-law. ¹
5. Noun. (rare) Niece of someone's husband. (Usually called a niece.) ¹
6. Noun. (rare) Niece of someone's wife. (Usually called a niece.) ¹
¹ Source: wiktionary.com