How I can add field with sale.order to crm.lead view?

I'm interesting filed untaxed_amount and I'd like add to view (model: crm.lead ; ref="crm.crm_case_kanban_view_leads"

I tried added to model with two model inheritance ['sale.order','crm.lead'] but I get informations, that the field amount_untaxed doesn't existing in a crm.lead.