[TYPO3-commerce] select directmail categories

[Christian Bernet]

Hi

I want to add directmail categoires at the creation or editing of an 
address.
This means: if the customer orders something and typed in his billing 
address he can select a direct mail category.
With the hook getBillingAddress i can add a additional field for the 
directmail categoires.
But i think this is not the right place to do this because:
- i can't do some validation (for example if a customer must select at 
minimum one category)
- if a customer is loged in or has multiple addresses, this shoud be in the 
address.

Any ideas to do this? Or can someone add a new hook for this?

Thanks,
christian