Hi,

1. As per the requirement, we have the option to add multiple contact details in the contact module. in the same way, we can create this functionality in the CRM module

we can use the one2many field in the CRM module
child_ids = fields.One2many('res.partner.category', 'parent_id', string='Child Tags') and added the field in the xml to inherit the CRM view
<record id="crm_lead_view_form" model="ir.ui.view">
<field name="name">http://crm.lead.view.form.inheirt.module.name" target="_blank">crm.lead.view.form.inheirt.module.name</field>
    <field name="model">crm.lead</field>
    <field name="inherit_id" ref="crm.crm_lead_view_form"/>
    <field name="arch" type="xml">
       
        <xpath expr="//page[@name='lead']/group/group/field[@name='partner_name']" position="replace">
            <group>
                <field name="child_ids"/>
                //you need the kanban view you can use the same view in the res.partner model
            </group>

        </xpath>

    </field>
</record>

Hope it helps