I still don't understand why you want to add an extra date field if this field already excistst!
If you create an article the re is a date publishing field in the form!
To show or hide the publishing date on the index page, take a look at the settings. It is a setting to show/hide the date.
Within the article itself the date of publishing is also shown.
So therefore I really don't understand your question. A link to your website and perhaps an example screenprint to show what exactly you want would be more helpfull.
See:
http://www.xuups.com/modules/publisher/
http://www.maltasport.com/modules/intersport/category.php?categoryid=11/ (this a cloned version of publisher)