manufacture/mrp_bom_line_sequence/views/stock_view.xml

<?xml version="1.0" encoding="utf-8" ?>
<odoo>
    <record id="mrp_bom_form_view" model="ir.ui.view">
        <field name="name">mrp.bom.form</field>
        <field name="model">mrp.bom</field>
        <field name="inherit_id" ref="mrp.mrp_bom_form_view" />
        <field name="arch" type="xml">
            <xpath
                expr="//field[@name='bom_line_ids']//field[@name='sequence']"
                position="attributes"
            >
                <attributes name="widget">"handle"</attributes>
            </xpath>
        </field>
    </record>
    <record id="mrp_bom_form_view2" model="ir.ui.view">
        <field name="name">mrp.bom.form</field>
        <field name="model">mrp.bom</field>
        <field name="inherit_id" ref="mrp.mrp_bom_form_view" />
        <field name="arch" type="xml">
            <xpath
                expr="//field[@name='bom_line_ids']//field[@name='sequence']"
                position="after"
            >
                <field name="sequence2" />
            </xpath>
        </field>
    </record>
</odoo>