co-parent vs relation

co-parent

noun
  • A divorced or separated parent who shares custody with the other parent. 

  • A godparent. 

  • A parent in a same-sex couple. 

  • Someone who shares in the parenting of a child or children, such as 

verb
  • To act as a co-parent; to share custody of a child or children; to share in the responsibility of parenting a child or children. 

relation

noun
  • A member of one's extended family; a relative. 

  • The manner in which two things may be associated. 

  • A set of ordered tuples. 

  • A set of ordered tuples retrievable by a relational database; a table. 

  • The act of intercourse. 

  • Specifically, a set of ordered pairs; a binary relation. 

  • The act of relating a story. 

  • A statement of equality of two products of generators, used in the presentation of a group. 

  • A subobject of a product of objects. 

How often have the words co-parent and relation occurred in a corpus of books? (source: Google Ngram Viewer )