CREATE TABLE #tmp (Cust INT, ParentCust INT)
INSERT INTO #tmp VALUES (1,2),(2,3),(3,-1),(4,2),(5,4);

WITH cte (C, p) AS
(
   SELECT cast(Cust AS VARCHAR(MAX)), Cust
   FROM #tmp WHERE ParentCust = -1
   UNION ALL
   SELECT CAST(t.Cust AS VARCHAR(MAX)) + '|' + C,
   t.Cust
   FROM #tmp t INNER JOIN cte c ON c.p = t.ParentCust
)
SELECT REPLACE(REVERSE(c1.c),'|',' ') FROM cte c1 WHERE 
NOT EXISTS (SELECT * FROM CTE c2 WHERE c2.c LIKE '%'+c1.C AND c1.c <> c2.c)

CREATE TABLE #tmp (Cust INT, ParentCust INT)
INSERT INTO #tmp VALUES (1,2),(2,3),(3,-1),(4,2),(5,4);


WITH cte (c1,c2,c3,c4,cust,lvl,ParentCust, s) AS
(
   SELECT
      Cust,NULL,NULL,NULL,
      cust,
      1,
      ParentCust,
      cast(Cust AS VARCHAR(MAX))
   FROM
      #tmp
   WHERE
      ParentCust = -1
   UNION ALL
   SELECT 
      c.c1,
      CASE WHEN lvl = 1 THEN t.Cust ELSE c.c2 END,
      CASE WHEN lvl = 2 THEN t.Cust else c.c3 END,
      CASE WHEN lvl = 3 THEN t.Cust else c.c4 END,
      t.Cust,
      lvl+1,
      t.ParentCust,
      CAST(t.Cust AS VARCHAR(MAX)) + '|' + s
   FROM
      #tmp t INNER JOIN cte c ON c.Cust = t.ParentCust
)
SELECT c1,c2,c3,c4 FROM cte ct1
WHERE NOT EXISTS (SELECT * FROM CTE ct2 WHERE ct2.s LIKE '%'+ct1.s AND ct1.s <> ct2.s);

drop table #tmp;