Create an invoice as explained here

Send it to the SII or approve it for processing to TicketBAI

Duplicate the invoice
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Set the amount of the duplicated invoice to negative

Send it to the SII or approve it for processing to TicketBAI

Select the original invoice and convert it into a sales amendment invoice
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Set the new amount to be corrected to negative

Edit the SII/TicketBAI fields and select Substitution
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Send it to SII or approve it for processing to TicketBAI