You can create as many as administrative accounts as you want on your wordpress blog. And, depending on on whether or not that person already has an account there are two methods to add them to your blog. But prior to allowing others administrative access to your blog it’s important to consider the roles you may choose to assign to them.
As very few wordpress.com themes allow for automatically assigning names to multiple authors on posts one of the common questions volunteers on the forum are asked is how to achieve this.
These are the options available for you to choose from.
Important Update: Please see WordPress.com Authors Widget
(1) You can choose a theme that provides for and displays individual authors. There are theme reviews that can assist you in determining if a theme provides this “authors” feature. Look in the section titled “Display post author”.
(2) If the theme you prefer to use does not this feature then you can create a category for each author’s name.
(3) If the theme you prefer to use does not this feature then you can create a category called “Authors” as a “parent” category and then create “children” (Tom, Dick, Harry) sub-categories for each author’s name under the parent category Authors.
(4) Or if neither of the above options are suitable then you can have each author include a byline in the posts they create.