we need to add a second recipient to the Send invoice by email Function.

The user should not add another recipient manually.

i found solution like: https://www.odoo.com/es_ES/forum/ayuda-1/question/custom-recipient-email-using-email-compose-message-wizard-form-119933 but it seems that the mail function does ignore the email_to field.

it seems only to work with the assigned partner_ids.

any ideas how to change/modify the email_to while generating the email without using the partner_ids?