>SELECT                   m.Numero
>FROM                     dbo.ChildTable AS c
>LEFT JOIN   dbo.ManyToManyTable AS mm ON mm.NoChildTable = c.Numero
>LEFT JOIN   dbo.[Master] AS m ON m.Numero = mm.NoMaster
>GROUP BY    m.Numero
>HAVING                   COUNT(c.Numero) <= COUNT(m.Numero)
>                         AND MIN(CASE WHEN c.[Enabled] = 1 THEN 1 ELSE 0 END) = 1