As you have discovered, the Numbering button cannot be
trusted. It seems to apply the previously used numbering
scheme, and thus gives you no control.

Actually, the only way to get in control, that is, to keep
track of numbering, in Word is to use styles. If you don't
use styles, there is no way to tell which numbering scheme
is applied to text, because two numbering schemes may look
identical without actually being identical. If you do use
numbered styles, you can always be sure that two
paragraphs using the same numbered style is part of the
same numbered list. (The rule here is, for single-level
numbering, that one list corresponds to one paragraph
style. For outline numbering, one list level should
correspond to one paragraph style.)

If you want to make it easier for your users to apply the
correct numbered styles, you can create toolbar buttons
(with descriptive captions) that applies the proper styles.

Stefan