it's not just a tag translation, this needs to be added as a new token for the template. are you familiar with PHP?

Yes PHP is fine. We already have a template override for invoice, just tell me what needs to be added.
I also sent you an email on a custom request, did you get it ?
Thanks

the file is /components/com_invoices/views/invoice/tmpl/default.php

there, we define all the token (tags) that can be added, and we define what they should be replaced with.

Thanks but you could explain a little more...

How do you load the joomla id from the user if it exists ? do you have a function for this or do I have to write a DB query directly in the template ?

BTW you did not reply neither to our request for custom coding neither for the CBsubs plugin that I sent...

OK have set a DB query to get the correct user id but in this case output by PDF or output in Admin backend does not display it as you use standard component front end template in admin.

Do you have a cleaner option or do we have to make an override also for Isis backend template ?

no, it's not a template you need to override, it's from the frontend indeed.
it's a bit more complicated I'm afraid... you need to add the token into the file I mentioned, but if you want it for "live preview" (on backend) you also need to add it into the function called "templateToVue" which is defined in file /components/com_invoices/helpers/helpers.php

Ok got it
Mind to reply to our email asking for quotes also ?