Hi,

You can super the create method of the model maintenance.equipment and then search the record in the model  assets.creation (based on the relation) and write values into it.

@api.model
def create(self, vals):
    res = super(Classname, self).create(vals)
    #Here you can search the record in the another model
    #In the vals you will get the required values 
    #and write the values into it
    return res

Also while posting the question use meaning full titles.
Thanks

class MaintenanceEquipment(models.Model):
    _inherit = "maintenance.equipment"

      owner_user_id = fields.Many2one('res.users', string='Assignee',readonly=False)

      @api.model

      def create(self.vals)

          obj = super(MaintenanceEquipment, self).create(vals)

          print('XYZ', vals)

          if obj.owner_user_id:

              print('check in terminal for debugging', obj.owner_user_id)

              obj.owner_user_id.owner_user_id1 = obj.owner_user_id.id

          return obj

Go to front-end and do the following steps to see the result.

1. Go "assets.creation" object, and create one record. (here is your owner_user_id1 field in which you get the value by default.

2. Open link in new tab and go to "maintenance.equipment", create record and also fill owner_user_id as you want it to be print in "owner_user_id1".

3. Refresh the window of "assets.creation".

Thanks

Adesh Paul

https://stackoverflow.com/questions/34171367/remove-create-and-edit-from-many2one-fieldlot-id-for-type-outgoing-using-f

I think this link will help you.