SQL - Inventory investigation - PostST vs AccBlnc

SELECT Diff = DmC - DMC2, P.*, G.*, A.Master_Sub_Account,A.Description,AT.cAccountTypeDescription, P3.dPeriodDate FROM (
	select G.SalesAccLink,PP.idPeriod, SUM(P.Debit-P.Credit) as DmC from PostST P 
		LEFT JOIN StkItem S ON P.AccountLink = S.StockLink
		LEFT JOIN _etblStockDetails SD ON S.StockLink = SD.StockID
		LEFT JOIN GrpTbl G ON SD.GroupID = G.idGrpTbl
		LEFT JOIN (SELECT DATEADD(day,1,P2.dPeriodDate) as FromDate, P.* FROM _etblPeriod P LEFT JOIN _etblPeriod P2 ON P.idPeriod-1 = P2.idPeriod) PP ON P.TxDate BETWEEN PP.FromDate and PP.dPeriodDate
		where Id IN ('oInv','Crn') AND TxDate >= '2021-03-01'
		group by G.SalesAccLink,PP.idPeriod) P
	RIGHT OUTER JOIN (
		select AB.iAccBlncAccountID, AB.iAccBlncPeriodID,SUM(AB.fActualDebit-AB.fActualCredit) as DMC2 from _etblAccBlnc AB
			left join Accounts A ON AB.iAccBlncAccountID = A.AccountLink
			LEFT JOIN _etblGLAccountTypes AT ON A.iAccountType = AT.idGLAccountType
			WHERE AT.cAccountTypeDescription like 'Reve%'
				AND AB.iAccBlncCurrencyID = 0
				GROUP BY AB.iAccBlncAccountID, AB.iAccBlncPeriodID
			) G ON (G.iAccBlncAccountID = P.SalesAccLink AND G.iAccBlncPeriodID = P.idPeriod)
	LEFT JOIN _etblPeriod P3 ON P3.idPeriod = COALESCE(P.idPeriod,G.iAccBlncPeriodID,0)
	left join Accounts A ON COALESCE(G.iAccBlncAccountID,P.SalesAccLink) = A.AccountLink
	LEFT JOIN _etblGLAccountTypes AT ON A.iAccountType = AT.idGLAccountType
	WHERE P3.idPeriod >= 109