How to enable a usage based subscription with estimated quantities without having to add the actuals

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Hi,

We have a requirement to create a monthly estimated invoice for usage of a vehicle (km).

The client wants to invoice each month an estimated amount and, at year end, they want to create a correction invoice based on the actual usage of that vehicle (credit note or a new invoice if the actual usage is higher than the estimated one).

How we can achieve this without having to import each month the actuals in the subscription management?

We have also tested the possibility to use a recurring charge type (not usage), but the quantity is not sent to AR. Instead of the actual quantity which we want to bill each month, subscription management sends quantity as 1 and the unit price as the total value (e.g. At subscription creation, we added a quantity 10000 and the unit price is unit price 0.0555 = 555.00 / per month. The line sent to AR is quantity 1 with unit price as 555.00).