I want to add a smart button on sales module in Odoo 12, when i click on it,it displays the overdue invoices of that customer i have already tried to do it by inheriting the sales module but its not

how to add button near smart button and after click open new form and pass value through form also show that value in form(odoo12).

The form buttons are always shown at the top of the form and are very handy to perform actions on your current record. After this tutorial you can create your own buttons and actions behind the buttons. 1. Creating your model and fields. The first step th