Only paragraph and character styles show up in the Styles group on the Home tab.
The recommended approach to multilevel numbering is to link each level of the list format to a paragraph style; then you can have the paragraph styles show up in the Styles group. See
http://www.shaunakelly.com/word/numb...g20072010.html, which uses the heading styles as an example, but the principles apply to any set of numbered styles.