Was M2 a person whose sibling founded M0 and M1
SELECT count(*) WHERE {
?x0 ns:organization.organization_founder.organizations_founded M0 .
?x0 ns:organization.organization_founder.organizations_founded M1 .
FILTER ( M2 != ?x0 ) .
M2 a ns:people.person .
M2 ns:people.person.sibling_s/ns:people.sibling_relationship.sibling|ns:fictional_universe.fictional_character.siblings/ns:fictional_universe.sibling_relationship_of_fictional_characters.siblings ?x0
}