Keep also in mind that in QV you can link 2 tables with 1 field only.
However, this key field can be a combination of several fields. For example:
Scenario1: invoice detail linked through InvoiceNo to invoice header
Scenario2: company, transaction type and transaction number constitute the key
Company & ' | ' & TrxType & ' | ' & TrxNo as TrxKey,
Load Company & ' | ' & TrxType & ' | ' & TrxNo as TrxKey,
After validating your links, you can consider using the autonumber function to store the key field as a number instead of string (for performance):
AutoNumber(Company & ' | ' & TrxType & ' | ' & TrxNo, 'TrxCounter') as TrxKey.
Hope this helps you.