[aposi]

Solo tienes que poner el segundo select dentro del primero con la union del codigo de articulo

Código SQL [-]
SELECT     p.CVE_ART, p.EXIST - 
(
SELECT     SUM(a.CANT) AS CANTIDAD
FROM         PAR_FACTP02 AS a LEFT OUTER JOIN
                      FACTP02 AS b ON a.CVE_DOC = b.CVE_DOC
WHERE     (b.STATUS <> 'C') AND (a.APAR <> 0) and (a.CVE_ART = P.CVE_ART) 
GROUP BY a.CVE_ART

)
FROM         MULT02 P
WHERE     (p.CVE_ALM = 1) AND (p.EXIST > 0)