Our developer make a custom module where it has force_date field, he want to update the dates in account.invoice date, sale.order date and the stock.picking date base on the force_date field value but in different module which I will create later on, a new module.

I'm still new to the environment of Odoo so It's really difficult for me, especially in inheriting coz I haven't try it yet, inheriting another module. 

Even just the pseudo code on how to do it will be a big help, if i still need to create a xml for the extension. Thank u :)