DECLARE @x XML;
SET @x = 'Your XML here';

SELECT
   IDENTITY(int,1,1) AS SourceId,
   c.value('@ResponseId','varchar(32)') ResponseId,
   c.value('@ParticipentId','varchar(32)') ParticipentId,
   c.value('@ReceiverId','varchar(32)') ReceiverId
INTO #tmp1
FROM
   @x.nodes('//Header') T(c);
   
DECLARE @sourceId INT = SCOPE_IDENTITY();
SELECT
   @sourceId AS SourceId,
   IDENTITY(INT,1,1) AS SID,
   c.value('@PBMName','varchar(32)') AS PBMName
INTO #tmp2
FROM
   @x.nodes('//Source') T(c)

SELECT * FROM #tmp1;
SELECT * FROM #tmp2;
DROP TABLE #tmp1;
DROP TABLE #tmp2;

DECLARE @x XML;
SET @x = 'Your XML here';

SELECT
	c.value('@ResponseId','varchar(32)') ResponseId,
	c.value('@ParticipentId','varchar(32)') ParticipentId,
	c.value('@ReceiverId','varchar(32)') ReceiverId,
	c2.value('@PBMName','varchar(32)') PBMName
INTO #tmp
FROM
	@x.nodes('//Header') T(c)
	CROSS APPLY c.nodes('//Source') S(c2)
SELECT * FROM #tmp;

---
-- Populate the two target tables here from data in #tmp
---
DROP TABLE #tmp;