Razesdark

This plugin will allow all authors to have their own tweets shown on in the widget area of their posts, by adding it to their profiles. 
That way any multi-author blog can let their bloggers promote their own twitter account and not a joint account.

Author Based Twitter Widget

A Author based twitter widget, made to help multi author blogs have individual twitter widgets for their authors.

itcoderr

When it comes to Blogging and online publishing, WordPress CMS is the go-to choice for individuals and large multi-authors publications. While managing your website, It would be hard for you to maintain and manage multiple contributors working on the same article. “Post Co-Authors” Plugin will help you to add multiple authors within same post, which makes the Job lots easier for you to track.
Add writers as bylines without creating WordPress user accounts. Simply create a user profile for the writer and assign the byline as you normally would.

Post Co-Authors

Post Co-Authors plugin allows you to select more then one authors in any post or custom post type.

Author Based Twitter Widget vs Post Co-Authors