ability to create one invoice line for each billing event

Summary:

We are creating multiple billing events, with same date, using REST API. These events have item on them.
When the draft invoice is generated, each billing event should be an invoice line (so if there are 10 billing events, there should be 10 invoice lines) on one invoice.

We are using Event number as grouping option (see attached) but still all the events are getting clubbed into one invoice line.

We need the ability to create one invoice line for each billing event on the same invoice.

Pls advise.

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