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.