Hi,

To allow users to enter the extended amount on vendor bill lines in Odoo and have the system back-calculate the unit price, you need to customize the account.move.line model and its form view. Create a custom module that depends on the account module. Add an extended_amount field to the account.move.line model and override the onchange method to calculate the price_unit based on the extended_amount and quantity.

In the module's view file, inherit the account.view_move_line_form view and add the extended_amount field before the price_unit field. Be mindful of rounding issues and consider disabling the price_unit field for clarity. Also, add a recompute rule to the price_subtotal field to ensure it is correctly calculated after the price_unit is updated. Install the module to apply the changes.

Python

from odoo import models, fields, api

class AccountMoveLine(models.Model):

    _inherit = 'account.move.line'

    extended_amount = fields.Monetary(string="Extended Amount", currency_field='currency_id')

    @api.onchange('extended_amount', 'quantity')

    def _onchange_extended_amount(self):

        if self.quantity and self.extended_amount:

            self.price_unit = self.extended_amount / self.quantity

        else:

            self.price_unit = 0.0

Hope it helps

You can probably achieve the same level of control by using the Accounting Firms mode.

See https://www.odoo.com/documentation/19.0/applications/finance/accounting.html#fiduciaries