How to create odoo 12 website submenu through code?

Question

I would like to create submenu under About Us main menu. I am trying with following code but it is adding main menu.

<!-- Main Menu ABOUT US -->
    <record id="menu_about_us" model="website.menu">
        <field name="name">ABOUT US</field>
        <field name="page_id" ref="about-us" />
        <field name="parent_id" ref="website.main_menu" />
        <field name="sequence" type="int">10</field>
    </record>
    <!-- Sub Menu Under ABOUT US -->
    <record id="menu_board_and_founders" model="website.menu">
        <field name="name">BOARD AND FOUNDERS</field>
        <field name="page_id" ref="board-and-founders" />
        <field name="parent_id" ref="menu_about_us" />
        <field name="sequence" type="int">10</field>
    </record>