Hi nohaAhmad,

Yes in order to inherit multiple model you can define it just like your question, however you need to define a new _name for your inherited models like so :

class Multi(models.Model):

    _name = 'sale.order'
    _inherit = ['sale.order', 'mail.thread']

    new_field = fields.Char("test")

The code above will re-define sale.order by inheriting sale.order model and adding a new mail.thread model. it is actually not recommended doing that way, since code above will redefine the sale.order with your custom module. as odoo suggest, we should rather inherit the existing code (extending it) rather than redefine it.

To properly inherit modeol, you need to define different class and define the different inherit. You need to inherit model1 and model 2 in different class like this :

class InheritModel1(models.Model):

    _inherit = ['model1']

    new_field = fields.Integer()
    
class InheritModel2(models.Model):

    _inherit = ['model2']

    new_field = fields.Integer()

The code above will create a new_field in model1 and model2. The new_field is independently created to each module you are inherited.

Hope this helpful, best regards,

Altela (altelasoftware.com)