library/library_member/views/book_view.xml

<?xml version="1.0"?>
<odoo>
    <record id="view_form_book_extend" model="ir.ui.view">
        <field name="name">Book: add Is Available? field</field>
        <field name="model">library.book</field>
        <field name="inherit_id" ref="library_app.view_form_book" />
        <field name="arch" type="xml">
            <!--<field name="isbn" position="after">-->
                <!--<field name="is_available" />-->
            <!--</field>-->
            <xpath expr="//field[@name='isbn']" position="after">
                <field name="is_available"/>
            </xpath>
        </field>
    </record>
</odoo>