Hi Marychan,

Try following code

class TestClass1(models.Model):
    _name = 'test.class1'

    name1 = fields.Char()

    @api.multi
    def my_new_fun(self):
        print(self.name1)
        # Your Main Class Method


class TestClass2(models.Model):
    _name = 'test.class2'

    name2 = fields.Char()


class TestClass3(models.Model):
    _inherit = ['test.class1', 'test.class2']

    @api.multi
    def my_new_fun(self):
        # You can Add your Functionality and also you can access name1 and name2 Variables here
        print(self.name1, self.name2)
        return super(TestClass3, self).my_new_fun()

Thanks.