In Greece, when an invoice's subtotal is bigger than 300 euros, the client has to prepay a tax. The prepaid tax has to be printed in the invoice, f.e. if the amount is 500 euros I print in the invoice "Prepaid tax 100 euros".
In the invoicepdf.tpl I have added a script that does the above (when the subtotal is bigger than 300 euros it counts and prints the tax).
In some cases this is not required.
So, I would like to add a select box (Auto or Default / Yes / No) in every invoice.
When the select box is set to auto, the script in invoicepdf.tpl will count the prepaid tax.
If it is set to No it will not print anything.
If it is set to Yes it will count the tax for every amount.
The problem is that in case I add a profile custom field, it will have the same value for all the client's invoices, and I need to change this value in each invoice. For example, in the same client, in one invoice the select box value can be Yes and in another can be No.