As used in this chapter, unless the context otherwise indicates, the following terms have the following meanings.
1. Grandparent. "Grandparent" is a parent of a child's parent or the parent of the parent of a child's parent. "Grandparent" includes a parent of a child's parent whose parental rights have been terminated pursuant to Title 18‑C, section 9‑204 or Title 22, chapter 1071, subchapter 6, but only until the child's adoption.
2. Sufficient existing relationship. "Sufficient existing relationship" means a relationship involving extraordinary contact between a grandparent and a child, including but not limited to circumstances in which the grandparent has been a primary caregiver and custodian of the child for a significant period of time.