Code:
SELECT PrimaryCustomer.ContactFirstName, PrimaryCustomer.ContactLastName, PrimaryCustomer.Phone, PrimaryCustomer.Fax, PrimaryCustomer.VendorID, [Project Expenses].[Expense Date], [Project Expenses].[Expense Description], [Project Expenses].[Expense Code], [Project Expenses].[Expense Amount], SecondaryCustomer.CustJobNumber, Invoice.JobName, PrimaryCustomer.CustName, PrimaryCustomer.StreetAddress, PrimaryCustomer.StateProvince, PrimaryCustomer.City, PrimaryCustomer.ZipPostalCode, PrimaryCustomer.PONumber, PrimaryCustomer.CustJobNumber, SecondaryCustomer.CustName, SecondaryCustomer.CustJobNumber, PrimaryCustomer.Terms
FROM (Invoice INNER JOIN ([Project Expenses] INNER JOIN SecondaryCustomer ON [Project Expenses].JobNo = SecondaryCustomer.JobNo) ON Invoice.JobNo = [Project Expenses].JobNo) INNER JOIN PrimaryCustomer ON Invoice.JobNo = PrimaryCustomer.JobNo
GROUP BY PrimaryCustomer.ContactFirstName, PrimaryCustomer.ContactLastName, PrimaryCustomer.Phone, PrimaryCustomer.Fax, PrimaryCustomer.VendorID, [Project Expenses].[Expense Date], [Project Expenses].[Expense Description], [Project Expenses].[Expense Code], [Project Expenses].[Expense Amount], SecondaryCustomer.CustJobNumber, Invoice.JobName, PrimaryCustomer.CustName, PrimaryCustomer.StreetAddress, PrimaryCustomer.StateProvince, PrimaryCustomer.City, PrimaryCustomer.ZipPostalCode, PrimaryCustomer.PONumber, PrimaryCustomer.CustJobNumber, SecondaryCustomer.CustName, SecondaryCustomer.CustJobNumber, PrimaryCustomer.Terms, [Project Expenses].JobNo
HAVING ((([Project Expenses].[Expense Date]) Between [Forms]![Print Reports].[fmStartDate] And [Forms]![Print Reports].[fmEndDate]) AND (([Project Expenses].JobNo)=[Forms]![Print Reports].[JobNoCombo]))
ORDER BY [Project Expenses].[Expense Date];
The report explicitly uses PrimaryCustomer.CustName and SecondaryCustomer.CustName.