Was a person 's parent M1 's prequel 's editor
SELECT count(*) WHERE {
?x0 ns:film.editor.film ?x1 .
?x0 ns:people.person.children|ns:fictional_universe.fictional_character.children|ns:organization.organization.child/ns:organization.organization_relationship.child ?x2 .
?x1 ns:film.film.sequel M1 .
?x2 a ns:people.person
}