nephew by marriage, grandnephew, son of a sister-in-law, son of a brother-in-law
kinship (part of speech: noun)
father, mother, kin, ancestor, cousin, kinship, brotherhood, fraternity, family, kinfolk, niece, flesh, relation, motherhood, blood, lineage, fatherhood, maternity, aunt, sisterhood, sister, paternity, uncle, heredity, clan, brother, consanguinity, relative
- " I have no nephew Hector. - "Hector's Inheritance or The Boys of Smith Institute", Horatio Alger.
- And the leetle property, and the uncle, if you wish it; and the leetle nephew- and the leetle nephew- and the leetle nephew! - "The Claverings", Anthony Trollope.
- On his way to the police- station he met Mr. Lewis, deceased's nephew. - "The Queen Against Owen", Allen Upward.