i want to change "vin" field. 

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first model:

class SWVehicle(models.Model):

 _name = 'sw.vehicle' 

vin= fields.Char(string = "vin")

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second model

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class SwMain(models.Model): 

_name = 'sw.main' 

_inherit = ['sw.vehicle']

vehicles = fields.One2many(string='name', comodel_name='sw.vehicle', inverse_name='task_id', copy=True)

requested = fields.Char(string="requested")

last model:
class SwMainVehicle(models.Model):

 _name = 'sw.main.vehicle' 

task_id = fields.Many2one(comodel_name='sw.main')

vehicle_id = fields.Many2one(string='estate', comodel_name='sw.vehicle', required=True)

vin = fields.Char(string='VIN ', related="vehicle_id.vin")

vehicle form

 sw.vehicle 

this form: 

          ? how to access vehicle form ??????

I tried:---------
 

sw.main.inherit.vehicle 

sw.main

"{'required':[('requested','not in',('lease1','lease2'))]}" ---how to find

Thanks