add new tap in product.tem ####

[Gddora]

product_test.py
(The code works and there are no errors.
But when I select the product and Alternative products in the product.template
When I go to the purchase order and choose the product and enter the new tab (Alternative), other products appear to me other than the ones I previously chose)
so, any one help me !!
#######################

from odoo import models, fields, api

class product_test(models.Model):
_inherit = 'product.template'

name = fields.Char(string="Name")
alter_ids = fields.Many2many("product.product", "product_tmpl", string="Alternative Products")

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

prodct_alternaitve_ids = fields.Many2many("product.template", "product_id",string="Product Alternaitve")

@api.onchange('order_line')
def onchange_alter_ids(self):
test_list =[]
for rec in self:
if rec.order_line.product_id:
print(rec.product_id,"################")
alternative_products = rec.order_line.product_id.alter_ids

        for i in alternative_products:
           print(i.id,"@@@")
           test_list.append(i.id)
           print(test_list)
           rec.write({'prodct_alternaitve_ids': [(4, i.id)]})

xml File

#############

product.template.form product.template

    <!-- ###########################################PO############################# -->
     <record id="purchase_order_form_test" model="ir.ui.view">
        <field name="name">purchase.order.form</field>
        <field name="model">purchase.order</field>
        <field name="inherit_id" ref="purchase.purchase_order_form"/>
        <field name="arch" type="xml">
            <xpath expr="//page[@name='purchase_delivery_invoice']" position='after'>
                <page string="Alternaitve">
                        <field name='prodct_alternaitve_ids'/>
                </page>
            </xpath>
        </field>
    </record>
</data>