purchase_merge_views.xml

<odoo>

    <record id="purchase_merge_automatic_wizard_form" model="ir.ui.view">
        <field name='name'>purchase.merge.automatic.wizard.form</field>
        <field name='model'>purchase.merge.automatic.wizard</field>
        <field name='arch' type='xml'>
            <form string='Automatic Merge Wizard'>
                <sheet>
                    <group col="1">
                        <p class="oe_grey">
                            Selected purchase will be merged together.
                        </p>
                        <group col="2">
                            <field
                                name="dst_purchase_id"
                                domain="[('id', 'in', purchase_ids or False)]"
                            />
                        </group>
                        <field name="purchase_ids" nolabel="1" string="Purchase">
                            <tree>
                                <field name="name" />
                                <field name="date_order" />
                                <field name="date_planned" />
                                <field name="amount_total" />
                                <field name="state" />
                                <field name="invoice_status" />
                            </tree>
                        </field>
                    </group>
                </sheet>
                <footer>
                    <button
                        name='action_merge'
                        string='Merge Purchase'
                        class='oe_highlight'
                        type='object'
                    />
                    <button
                        special="cancel"
                        string="Cancel"
                        type="object"
                        class="btn btn-default oe_inline"
                    />
                </footer>
            </form>
        </field>
    </record>

    <record id="action_purchase_merge" model="ir.actions.act_window">
        <field name="name">Merge Selected Purchase</field>
        <field name="type">ir.actions.act_window</field>
        <field name="res_model">purchase.merge.automatic.wizard</field>
        <field name="view_mode">form</field>
        <field name="binding_model_id" ref="purchase.model_purchase_order" />
        <field name="target">new</field>
    </record>

</odoo>