how to add one more field in the billing address
I am making onlien shopping mall in Ecuador.
To make invoice, I need TAX ID by law of Ecuador government.
But in the customer address form when customer make order, there is no field of TAX ID.
To solve the problem, I added one field of TAX ID in creation of customer's account.
In my online mall, creation of customer's account is mandatory because it is only way to get customer's
but, when the address of customer and billing address is differen, customer has to inpurt billing address
informacon when he do checkout. but in the billing adrres form, there is no field to get TAX ID.
So, if possible, I would like to add one more field to get TAX ID when checkout.
please help me