Queries :: How To Edit Query Data

I have a table structure that I guess could be called a dual one-to-many-to-one, as can be seen in the attached Relationships screen print. Customer loan files are maintained in an AllFiles table, tied to the Customers and Loans tables through the CustomerFiles and LoanFiles tables. Users access the data from an unbound form called FileProcessing, where they can select a customer, and a loan for that customer. The files linked to that customer and loan then appear on a form called Files. However, I need the data on Files to be updateable, and I'm having a hard time coming up with a Files datasource that can be updated. The SQL that retrieves the needed data is:

Code:
SELECT AllFiles.*
FROM (AllFiles INNER JOIN CustomerFiles ON AllFiles.FileNum = CustomerFiles.FileNum)
INNER JOIN LoanFiles ON AllFiles.FileNum = LoanFiles.FileNum
WHERE LoanFiles.LoanNum=[Forms]![FileProcessing]![tbLoanNum]
AND CustomerFiles.CIFKey=[Forms]![FileProcessing]![tbLoanCIFKey];

I tried creating another query that just had the AllFiles table linked to the above query, but the data still couldn't be updated.