It looks like you really have as MM source a query (either created by you, or by 3rd party (Kallal's) app) like
Code:
SELECT cust.CustomerID, cust.CustomerName, ... , acc.CustomerAccountNr, acc.AcountNo, ... FROM tblCustomers cust LEFT OUTER JOIN tblAccounts acc ON acc.CustomerID = cust.CustomerID
The problem is, such query returns several records for customer, when customer has several accounts. And MM greates always a document per record!
You need for this document a separate saved query, like
Code:
SELECT
cust.CustomerID, cust.CustomerName, ... ,
acc1.CustomerAccountNr As AccountNr1, acc1.AccountNo As AccountNo1, ...,
acc2.CustomerAccountNr As AccountNr2, acc2.AccountNo As AccountNo2, ...,
acc3.CustomerAccountNr As AccountNr3, acc3.AccountNo As AccountNo3, ...,
...
FROM (((tblCustomers cust LEFT OUTER JOIN tblAccounts acc1 ON acc1.CustomerID = cust.CustomerID)
LEFT OUTER JOIN tblAccounts acc2 ON acc2.CustomerID = cust.CustomerID)
LEFT OUTER JOIN tblAccounts acc3 ON acc2.CustomerID = cust.CustomerID)
...
WHERE acc1.CustomerAccountNr = 1 AND acc2.CustomerAccountNr= 2 AND acc3.CustomerAccountNr= 3 ...