user is creating custom Invoice Print Layouts in excel and needs to add in some Order custom fields but there doesn't seem to be an option in the Excel Template.
There are codes to enter Billing, Invoice and Project custom fields, but no Order custom fields.
It is not possible to retrieve orders' information in the invoices/quotes. However one can retrieve projects' information, so the idea is to have the values of the order custom field copied automatically into project custom fields. This way one can have order information retrieved into invoices/quotes.
Here is the process, once order custom field is created in the 'new order form' configuration, for each option there is 'project settings' tab. Under this tab, there is Placeholder link, click it and copy the one corresponding to your order custom field:
Then, paste it in the field corresponding to your project custom field, as default value (this implies that you have created a project custom field (text field)):
Now modify invoice template (Settings>Invoice print layout), click 'help with customizing templates' to see which placeholder you need to copy into the template (<#ProjectCustomStr1/2/3...>):
Finally, paste the placeholder into the template, save your change, upload the template back into the platform.