Am trying to add multiple weak functionality in odoo 12. I've done it all but the only thing missing is that widget section_one2many. I tried to create this widget in by using js code of odoo 13 and giving its path in web.asset: like this,

<template id="assets_backend" name="calendar" inherit_id="web.assets_backend">
    <xpath expr="." position="inside">
        <script type="text/javascript" src="/two_weeks_calendar/static/src/js/fields_section_one2many.js"/>

    </xpath>
</template>
But this is not working. Still am not getting the functionality of this widget. Kindly help, Thanks in advance