Hi Jeck,
attached find a sample that lets you specify relations manually.
ManualRelations_2932.zip
With regards to foreign keys. In our next version we will have full support for specifying foreign keys and have the fields from the related table automatically be included into the main table. If you are interested in this we can give you access to interim builds (should have something ready soon) so you can check it out. Just open a direct trac incident if you are interested.
Stefan