The structure of a Custom URL creating a new Invoice is below, with all possible fields shown. Required fields are in red. All other fields are optional.
All Fields available for a New Invoice with Child Records
The list and structure of a Custom URL with all possible fields, including those for Line Items that are drawn from Child Records, utilized is below. Required fields are in red. All other fields are optional. Please note that many of these fields will not work unless the corresponding field is setup in the accounting system.
Please note that QBO only allows you to have a Class at the Invoice level or the Line Item level but not both. This must be set in QBO’s settings. Thus, the URL above for QBO will not work as it specifies the Class at the Invoice AND Line Item level. A working URL would require at least one of these to be removed.
Applying Payments
It is possible to specify a payment at the time of Invoice creation.
For QBO, you need to specify three fields
Amount Paid
Paid To
And you can optionally specify
Reference
This can only be done at the time of Invoice creation.