The new Library Member model should be in its own Python code file, but to keep the explanation as simple as possible, we will reuse the models/library_book.py file:

1. Add the new model, inheriting from res.partner:

class LibraryMember(models.Model): 
    _name = 'library.member' 
    _inherits = {'res.partner': 'partner_id'} 
    partner_id = fields.Many2one( 
        'res.partner', 
        ondelete='cascade')

2. Next, we will add the fields that are specific to Library Members:

# class LibraryMember(models.Model): 
    # ... 
    date_start = fields.Date('Member Since') 
    date_end = fields.Date('Termination Date') 
    member_number = fields.Char() 
    date_of_birth = fields.Date('Date of birth')

Now, we should upgrade the add-on module to activate the changes.