How to move a stream item to a specific group (via a database table)?

Would there be a simple way, via the database tables, to move a stream item to a group stream?

If it is just a matter of changing an item or two in a specific table, that sure would be useful for us (and easy to do) in getting our users to use the groups more. But I've been looking through the tables and am not finding something like a category field for stream items.

Please advise.

Thank you. -- Rik