Increase more lines for message to customers in invoice and have a special character in invoice num

danlapin

Hello, I would like to have more lines in message to customer in invoice and to have a special character in invoice. For example, if I provide 1 invoice with two parts for the same customer I would like to be able to add a special character. First invoice would be DL256_1 and the second would be DL256_2. Thank you