Hi,

You can use the following code to link a purchase order with its payments.

Python

from odoo import models


class PurchaseOrder(models.Model):
    _inherit = 'purchase.order'

    def button_get_payments_attachments(self):
        self.ensure_one()
        account_payment_ids = [
            item['account_payment_id']
            for payment in self.invoice_ids.mapped('invoice_payments_widget')
            for item in payment.get('content', [])
        ]
        return {
            'type': 'ir.actions.act_window',
            'name': 'Payments',
            'res_model': 'account.payment',
            'view_mode': 'tree,form',
            'domain': [('id', 'in', account_payment_ids)],

        }

Hope it helps