overriding inherited mapper properties supported?

[Kent]

Suppose I am using single table polymorphic inheritance like the docs Employee/Manager/Engineer example.  I have a relationship that I want to have a different cascade or loading strategy for, depending on the mapper.  Can I inherit from the base mapper and override the property, like this:

employee_mapper = mapper(Employee, employees_table, \
    polymorphic_on=employees_table.c.type, polymorphic_identity='employee',
    properties={'customer':relationship(Customer, lazy=False, cascade='save-update,refresh-expire,merge')})
manager_mapper = mapper(Manager, inherits=employee_mapper,
                                    polymorphic_identity='manager',
    properties={'customer':relationship(Customer, lazy=True, cascade='save-update,refresh-expire')})
engineer_mapper = mapper(Engineer, inherits=employee_mapper,
                                    polymorphic_identity='engineer',
    properties={'customer':relationship(Customer, lazy=True, cascade='save-update,refresh-expire')})


Here, the 'customer' relationship only joined loads and merges for Employee, not Engineer nor Manager.  Is this supported? 

[Michael Bayer]

it's not.