corporate theme - Home Articles Block with site-wide categories?

Using multisite and the corp theme, and under theme options, it looks like the Home Articles Block is pulling categories & posts only from the main blog.

I created an identical category name & slug on another blog on the site, and it does not appear under theme options and the post does not appear on the Home Articles Block section of the home page.

What is the best way to make that section pull the most recent post from a specific category site-wide?