Hi 123146529767419,
I can see your point on the need to have this set for selected customer and it makes sense why you would require this.
At the moment however, the custom field can be added to the invoice template and it applies to all invoices created in the system. It cannot be set-up for selected customers unfortunately.
Please let us know if you have further questions regarding this. We will be happy to help the best way we can.
Have a lovely Monday!
