co-second-cousin-in-law

Spouse's second-cousin's spouse.

co-second-cousin-in-law.

quadruple-half-cousin

1- Child of double-half-aunt (daughter of maternal grandmother and of paternal grandfather) and of double-half-uncle (son of paternal grandmother and of maternal grandfather) at the same time.
2- Child of double-half-aunt (daughter of paternal grandmother and of maternal grandfather) and of double-half-uncle (son of maternal grandmother and of paternal grandfather) at the same time.
3- Person who, in relation to the other person, has zero parents and four grandparents in common (in different manners that the double-first-cousin).
4- Quadruple-half-first-cousin.
5- Quadruple-half-1C.

My quadruple-half-cousin is a good person.

irregular-nonuple-fourth-cousin

Someone who, in relation to others, has zero parents, zero grandparents, zero great-grandparents, zero great-great-grandparents and seventeen great-great-great-grandparents in common.

Irregular-nonuple-fourth-cousin.

sesqui-cousin-nephew

Sesqui-first cousin’s son.

My sesqui-cousin-nephew is a good boy.

first cousin-nibling

First cousin's child.

My first cousin-nibling is a good person.

sesqui-great-cousin-niece

Sesqui-first cousin’s granddaughter.

My sesqui-great-cousin-niece is a good person.

step-cousin-niece

1. The granddaughter of one's parent's stepsibling.
2. The stepgranddaughter of one's parent's sibling.
3. The granddaughter of one's stepparent's sibling.

My step-cousin-niece is a good person.