Hello Svend,
If you setup a new address for your vendor you should be able to identify a "General" tab in the edit address form. There you are able to setup a different sales tax group that you require to get your taxes right if deliveries occur from different addresses/countries.
If you require additional purposes for your vendor addresses you can set them up in the Organization Administration module - Setup - Global Address Book - Addresses and contact Information purpose.
Hope it helps,
Ludwig