Well you really know how to do this but I think you might be trying for a magic bullet and I do not think it will work.

You simply have to cut and join a copy of the aphs you want to define the outer profile of the art and use that new art to create the offset path. It is a manually process. I guess there might possibly be a magic bullet but the time you find it you might have finished the job manually.

Just to set up an example, draw these objects near each other:

• A closed simple path (ex: Rectangle), solid fill, no stroke
• A compound path (ex: two compounded circles, solid fill, no stroke
• Duplicates of the above two objects, no fill, solid strokes of differing weights
• An open path, no fill , solid stroke

Now carefully do the following to create an offset outline. Be aware, the resulting outline will take on the stroke/fill of the frontmost path.
For example, if the frontmost path has a black stroke, fill of none, so will the resulting offset contour.

1. Select all the Paths.
2. Object>Group.
3. Edit>Copy.
4. Edit>Paste In Front.
5. Effect>Path>Outline Object.
6. Effect>Path>Offset Path. Offset: as desired. Joins: Round.
7. Effect>Pathfinder>Add.

Now store this as a Graphic Style:

8. Black pointer: Drag the Group and drop it into the Graphic Styles palette.
9. DoubleClick the Style’s icon. Set its name to “Offset Contour” (or whatever).

Now you can apply the same Graphic Style to a different Group with one click.
Graphic Styles are saved with the document. So if you want to use the same Style in other documents:

10. Graphic Styles flyout menu: Save Graphic Style Library...

By default, the Graphic Style Library will be written into the Graphic Styles folder of your user account. Example:
C:\Users\firstName.lastName\AppData\Roaming\Adobe\Adobe Illustrator CS5.1 Settings\en_US\Graphic Styles

You can later load it into a new document by Graphic Style palette flyout menu>Open Graphic Style Library>User Defined,
or by simply copying a Group to which the Style has been applied and pasting it into the new document.

After storing the Style for future use, expand it into an ordinary path (or compound path, depending on the artwork):

11. Object>Expand Appearance.
12. Ungroup.
13. Apply fill/stroke as desired.

Once you have created the Graphic Style, you can record an Action to automate the  whole thing, by recording these steps:

1. Steps 2-4
2. Application of the Offset Contour Style
3. Steps 11-13

Now you can create such an outline for any set of paths with a single click by selecting all the associated paths and clicking the Action.

JET