Jason,
Usually SQL is considered SET oriented instead of RECORD oriented. If you wanted to pull back the children for a specific parent, you'll specifically pass the parent's PK with the query against the child table. After SQL Server returns a result set to you, it has no idea what your doing with it.
SELECT * FROM child_table WHERE FK = FK_From_Parent
It's up to you to properly construct the query and submit it to the server.
-Mike