odoo16/addons/purchase_requisition/views/purchase_views.xml

<?xml version="1.0"?>
<odoo>

    <record id="purchase_order_form_inherit" model="ir.ui.view">
        <field name="name">purchase.order.form.inherit</field>
        <field name="model">purchase.order</field>
        <field name="inherit_id" ref="purchase.purchase_order_form"/>
        <field name="arch" type="xml">
            <field name="partner_id" position="replace">
                <field name="is_quantity_copy" invisible="1"/>
                <field name="partner_id" widget="res_partner_many2one" context="{'res_partner_search_mode': 'supplier', 'show_vat': True}" attrs="{'readonly': ['|', ('is_quantity_copy', '=', 'none'), ('state', 'in', ['purchase', 'done', 'cancel'])]}" placeholder="Name, TIN, Email, or Reference" force_save="1"/>
            </field>
            <field name="partner_ref" position="after">
                <field name="requisition_id" domain="[('state', 'in', ('in_progress', 'open', 'ongoing')), ('vendor_id', 'in', (partner_id, False)), ('company_id', '=', company_id)]"
                options="{'no_create': True}"/>
            </field>
            <xpath expr="//page[@name='purchase_delivery_invoice']" position="after">
                <page string="Alternatives" name="alternative_pos">
                    <group>
                        <group>
                            <p colspan="2">Create a call for tender by adding alternative request for quotations to different vendors.
                            Make your choice by selecting the best combination of lead time, OTD and/or total amount.
                            By comparing product lines you can also decide to order some products from one vendor and others from another vendor.</p>
                        </group>
                        <group>
                            <p colspan="2">
                                <button name="action_create_alternative" type="object" class="btn-link d-block" string="Create Alternative" icon="fa-copy"/>
                                <button name="action_compare_alternative_lines" type="object" class="btn-link d-block" string="Compare Product Lines" icon="fa-bar-chart" attrs="{'invisible': [('alternative_po_ids', '=', [])]}"/>
                            </p>
                        </group>
                    </group>
                    <field name="alternative_po_ids" attrs="{'readonly': [('id', '=', False)]}" widget="many2many_alt_pos" context="{'quotation_only': True}">
                        <tree string="Alternative Purchase Order" decoration-muted="state in ['cancel', 'purchase', 'done']" decoration-bf="id == parent.id">
                            <control>
                                <create string="Link to Existing RfQ"/>
                            </control>
                            <field name="partner_id"/>
                            <field name="name" string="Reference"/>
                            <field name="date_planned"/>
                            <field name="amount_total"/>
                            <field name="state"/>
                        </tree>
                    </field>
                </page>
            </xpath>
        </field>
    </record>

    <record id="purchase_order_search_inherit" model="ir.ui.view">
        <field name="name">purchase.order.list.select.inherit</field>
        <field name="model">purchase.order</field>
        <field name="inherit_id" ref="purchase.view_purchase_order_filter"/>
        <field name="arch" type="xml">
            <xpath expr="//filter[@name='approved']" position="after">
                <filter string="Requisition" name="requisition" domain="[('requisition_id', '!=', False)]"  help="Purchase Orders with requisition"/>
            </xpath>
        </field>
    </record>

    <record id="purchase_order_kpis_tree_inherit_purchase_requisition" model="ir.ui.view">
        <field name="name">purchase.order.kpis.tree.inherit.purchase.requisition</field>
        <field name="model">purchase.order</field>
        <field name="inherit_id" ref="purchase.purchase_order_kpis_tree"/>
        <field name="arch" type="xml">
            <field name="name" position="before">
                <field name="has_alternatives" invisible="1"/>
                <button class="fa fa-copy"
                    title="Has Alternatives"
                    disabled="1"
                    attrs="{'invisible': [('has_alternatives', '=', False)]}"/>
            </field>
        </field>
    </record>

    <record id="purchase_order_tree_inherit_purchase_requisition" model="ir.ui.view">
        <field name="name">purchase.order.tree.inherit.purchase.requisition</field>
        <field name="model">purchase.order</field>
        <field name="inherit_id" ref="purchase.purchase_order_tree"/>
        <field name="arch" type="xml">
            <field name="name" position="before">
                <field name="has_alternatives" invisible="1"/>
                <button class="fa fa-copy"
                    title="Has Alternatives"
                    disabled="1"
                    attrs="{'invisible': [('has_alternatives', '=', False)]}"/>
            </field>
        </field>
    </record>

    <record id="purchase_order_line_compare_tree" model="ir.ui.view">
        <field name="name">purchase.order.line.compare.tree</field>
        <field name="model">purchase.order.line</field>
        <field name="priority">1000</field>
        <field name="arch" type="xml">
            <tree string="Purchase Order Lines"
            decoration-muted="state in ['cancel', 'purchase', 'done']"
                create="0" delete="0" edit="0" expand="1"
                js_class="purchase_order_line_compare">
                <header>
                    <button name="action_clear_quantities" string="Clear Selected" type="object" class="o_clear_qty_buttons"/>
                </header>
                <field name="product_id" readonly="1"/>
                <field name="partner_id" string="Vendor"/>
                <field name="order_id" string="Reference" readonly="1"/>
                <field name="state"/>
                <field name="name" readonly="1"/>
                <field name="date_planned" readonly="1"/>
                <field name="product_qty"/>
                <field name="product_uom" groups="uom.group_uom"/>
                <field name="price_unit"/>
                <field name="price_subtotal" string="Total"/>
                <field name="currency_id"/>
                <button name="action_choose" string="Choose" type="object" class="o_clear_qty_buttons" icon="fa-bullseye"
                    attrs="{'invisible': [('product_qty', '&lt;=', 0.0)]}"/>
                <button name="action_clear_quantities" string="Clear" type="object" class="o_clear_qty_buttons" icon="fa-times"
                    attrs="{'invisible': ['|', ('product_qty', '&lt;=', 0.0), ('state', 'in', ['cancel', 'purchase', 'done'])]}"/>
            </tree>
        </field>
    </record>

</odoo>