Double-second-cousin: has among themselves; different two parents, different four grandparents, four great-grandparents in common and different four great-grandparents.
Double-third-cousin: has among themselves; different two parents, different four grandparents, different eight great-grandparents, four great-great-grandparents in common and different twelve great-great-grandparents.
Double-first-cousin-once-removed: child of their grandparent’s full sibling with the other grandparent’s full sibling or child of their maternal first cousin with the paternal first cousin or double-first cousin’s child or child of their parent's parent's full sibling with the other parent’s full sibling's child.
Double-first-cousin-twice-removed: child of their great-grandparent’s full sibling with the other great-grandparent’s full sibling or grandchild of their maternal first cousin with the paternal first cousin or double-first cousin’s grandchild or child of their parent's grandparent's full sibling with the other parent’s full sibling's grandchild or child of their parent's parent's sibling's child with the other parent’s sibling's child's child.