Combining Detail Records From Different Tables

Following is a stored procedure that currently runs on the system (compacted version). I need to combine this data with data from another Table .. tblAdjustments. The schema for this table is fairly close to tblShipmentDet.

tblShipmentHdr --> tblShipmentDet (Key = ShipmentID)
tblAdjustments --> standalone

Result: combine tblShipmentHdr + attached tblShipmentDet records with
tblAdjustments records.

Would the best approach be to use a UNION SELECT?

@XToDate datetime = '7/31/2005' ,@XBegDate datetime = '7/1/2005'
AS
SELECT
SHPH.ProductID,
SHPH.ReceivedDate,
SHPH.ShipmentNo,
SHPD.Vendor,
SHPD.Quantity,
QRecvdDate = CASE WHEN SHPH.ReceivedDate < convert(varchar(40),@XBegDate,121)
THEN NULL ELSE SHPH.ReceivedDate
END,
QShipQty = CASE WHEN SHPD.TransCd = 'F'
THEN NULL
WHEN SHPH.ReceivedDate < convert(varchar(40),@XBegDate,121)
THEN NULL
ELSE SHPH.ShippingQty
END,
PROD.ProductName,
QOpenAccrual = CASE WHEN MEND.OpeningAccrual is Null
THEN 0 ELSE MEND.OpeningAccrual
END
FROM dbo.tblShipmentHdr SHPH
LEFT OUTER JOIN dbo.tblProducts as PROD ON Left(SHPH.ProductID,7) = Left(PROD.ProductID,7)
LEFT OUTER JOIN dbo.tblShipmentDet as SHPD ON SHPH.ShipmentID = SHPD.ShipmentID
LEFT OUTER JOIN dbo.tblMonthend as MEND ON SHPH.ProductID = MEND.ProductID And MEND.MEPeriod = convert(varchar(40),@XBegDate,121)
WHERE ((SHPH.ReceivedDate >= '7/1/2005' AND SHPH.ReceivedDate <= '7/31/2005') OR (SHPD.DatePaid >= '7/1/2005' AND SHPD.DatePaid <= '7/31/2005'))