suite/rma_sale/views/rma_views.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>

    <!-- RMA Template -->
    <record id="view_rma_template_form_sale" model="ir.ui.view">
        <field name="name">rma.template.form.sale</field>
        <field name="model">rma.template</field>
        <field name="inherit_id" ref="rma.view_rma_template_form"/>
        <field name="arch" type="xml">
            <xpath expr="//field[@name='usage']" position="after">
                <field name="so_decrement_order_qty" string="Decrement Ordered Qty" attrs="{'invisible': [('usage', '!=', 'sale_order')]}"/>
                <field name="sale_order_warranty" string="Warranty" attrs="{'invisible': [('usage', '!=', 'sale_order')]}"/>
            </xpath>
        </field>
    </record>

    <!-- RMA -->
    <record id="view_rma_rma_form_sale" model="ir.ui.view">
        <field name="name">rma.rma.form.sale</field>
        <field name="model">rma.rma</field>
        <field name="inherit_id" ref="rma.view_rma_rma_form"/>
        <field name="arch" type="xml">
            <xpath expr="//div[@name='button_box']" position="inside">
                <button class="oe_stat_button" name="open_sale_order_rmas" icon="fa-cubes"
                        type="object" attrs="{'invisible': ['|', ('sale_order_id', '=', False), ('sale_order_rma_count', '&lt;=', 1)]}">
                    <field name="sale_order_rma_count" string="SO RMAs" widget="statinfo" />
                </button>
            </xpath>
            <xpath expr="//field[@name='template_id']" position="after">
                <field name="sale_order_id" options="{'no_create': True}" attrs="{'invisible': [('template_usage', '!=', 'sale_order')], 'required': [('template_usage', '=', 'sale_order')], 'readonly': [('state', 'in', ('confirmed', 'done', 'cancel'))]}"/>
                <br/>
                <button string="Add lines" type="object" name="action_add_so_lines" attrs="{'invisible': ['|', ('sale_order_id', '=', False), ('state', '!=', 'draft')]}"/>
            </xpath>
        </field>
    </record>

    <record id="view_rma_rma_tree_sale" model="ir.ui.view">
        <field name="name">rma.rma.tree.sale</field>
        <field name="model">rma.rma</field>
        <field name="inherit_id" ref="rma.view_rma_rma_tree"/>
        <field name="arch" type="xml">
            <xpath expr="//field[@name='template_id']" position="after">
                <field name="sale_order_id"/>
            </xpath>
        </field>
    </record>

    <record id="view_rma_rma_search_sale" model="ir.ui.view">
        <field name="name">rma.rma.tree.sale</field>
        <field name="model">rma.rma</field>
        <field name="inherit_id" ref="rma.view_rma_rma_search"/>
        <field name="arch" type="xml">
            <xpath expr="//field[@name='template_id']" position="after">
                <field name="sale_order_id"/>
            </xpath>
        </field>
    </record>

    <menuitem
        action="rma.action_rma_rma"
        id="menu_action_sales_rma_form"
        parent="sale.sale_order_menu"
        sequence="12"
        />

    <menuitem
        action="rma.action_rma_template_form"
        id="menu_action_sales_rma_template_form"
        parent="sale.menu_sale_config"
        sequence="12"
        />
    <menuitem
        action="rma.action_rma_tag_form"
        id="menu_action_sales_rma_tag_form"
        parent="sale.menu_sale_config"
        sequence="12"
        />
</odoo>