SELECT  DISTINCT astops.name, cstops.name FROM
  route a JOIN route b ON a.company=b.company AND a.num = b.num
              JOIN route c ON b.company=c.company AND b.num = c.num AND b.stop = c.stop
              JOIN stops astops ON a.stop = astops.id
              JOIN stops bstops ON b.stop = bstops.id
              JOIN stops cstops ON c.stop = cstops.id
WHERE astops.name = 'Craiglockhart' AND cstops.name = 'Sighthill'