That is exactly what I would recommend. And label the entries in accounts receivable / payable something like:
- “Implied invoice”
- “Implied payment” or “Implied receipt”
The reasons
A “cash” transaction in Manager is when the supplier does not extend credit to the customer. It is equivalent to generating an invoice with zero days payment requirement and the customer paying prior to leaving the counter.
An even more common situation is a physical invoice is generated and supplied however the Manager user enters the data by importing a bank statement and allocating the payment directly to the profit & loss account. An efficient method however if entered fully it would have gone through Accounts payable / receivable.
In either case an invoice could have been entered in Manager with the resulting credit and debit entry.
Manager actually doing that ensures all transactions appear logically together in existing reports independent of what mix of Manager invoices a user chooses to enter.
Edit
Expanded on accounts receivable / payable labelling.