TDM allows you to select a table or set of tables. You can select tables from different schemas, multiple filtering is available (in latest Beta and upcoming full v. 3.5).
However, TDM cannot display tables that directly join to the selected tables.
We recommend you to check out Toad for Oracle - this feature should be available in ER Diagrammer (or via Schema Browser and Description Window).
Feel free to ask for current Toad for Oracle trial version or Beta (trial or full key is required for Beta). Latest Beta has brought some enhancements of this functionality.
So, let me redirect you to the Toad for Oracle community:
Note: TDM and Toad are integrated. You can RE your tables to Toad. Then import Toad ERD to TDM and work with it in TDM.
Vladka + TDM Team