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Mostly it depends on the internal policy when and which optimization type to use as well as which invoice cancellation type to choose.
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The following invoice cancellation types are available
Standard cancellation
Fully cancel the related invoices completely
Issues new correct invoices
Merge periods cancellation
Cancels only line items for changed Campaign Item out of all related invoices
Invoice items which related to other Campaign Items but the same invoices will not get cancelled
Issue one credit note for all changed Campaign Items in the current period
Create a new invoice for the changed Campaign Item per period
Merge all cancellation
Merge all changes for related Campaign items in the next outstanding PreInvoice
When there are no outstanding Preinvoices, create only 1 Preinvoice for all changes in the current period
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