You don't say what software you are using.
In MLCad for example, on the "Add Part" dialog, you can tick "Custom Part" and then manually browse a part from any folder. This is one way of adding parts that are not part of the official library (if that's what you mean by "extra parts").
In MLCad for example, on the "Add Part" dialog, you can tick "Custom Part" and then manually browse a part from any folder. This is one way of adding parts that are not part of the official library (if that's what you mean by "extra parts").