library/library_website/views/library_member.xml

<?xml version="1.0" encoding="UTF-8" ?>
<odoo>
    <record id="view_form_member" model="ir.ui.view">
        <field name="name">Member Form</field>
        <field name="model">library.member</field>
        <field name="inherit_id" ref="library_member.view_form_member"/>
        <field name="arch" type="xml">
            <field name="card_number" position="after">
                <field name="user_id"/>
            </field>
        </field>
    </record>
</odoo>