Permissions for multi-author nodes
Many of the permissions related to nodes draws on a single-user concept of authorship. The way Drupal defines whether a node “belongs” to someone (e.g. for “delete own content”) is whether the user’s name appears in the “Authored by” field, under “Authoring information” at the bottom of the node creation and editing screen. There is no way to put more than one username in that field.
Even though Drupal does not technically support multi-author arrangements, many projects contain material that was created by more than one person. The Node Access User Reference module provides a way to give more than one user the rights reserved for the singular “author” of a particular node.
If you try to enable Node Access User Reference without first enabling User Reference (part of the References module package) or Entity reference (an alternative to References), a warning will appear and Node Access User Reference won’t be enabled. You must also click the “rebuild permissions” link before Node Access User Reference options will be available as part of the configuration for a user reference field.
Once you have done this, edit an existing user reference field in the content type where you want to allow multiple users to have “author” level permissions, or create a new user reference field. Under the help text box, a toggle-down menu for “Node access user reference” will appear.
The first set of checkboxes, “Grants for referenced users on the node”, will be the most useful. If you check “update” and/or “delete”, users referenced in this field will be able to update and/or delete the node, even if you haven’t configured general permissions so that anyone can edit or delete any node. You can set it so referenced users’ heightened permissions only apply after the node is published, or they can apply to published and unpublished nodes. The second set of checkboxes, “Grants for referenced users to create content”, is less useful. In most cases, you’ll want to use roles to define who can create what content types.
Keep in mind that this module only addresses the permissions-related aspects of a multi-author situation. If you have enabled the display of author and date information for the content type (see section 6.2.3), the user who actually created the node on the site will still be listed as the one and only author. To get multiple authors in a user reference field to display as multiple authors, hide author and date information for the content type. You may want to use Display Suite or CCK blocks (see section 9.3.1), and/or Views (see chapters 12 and 13) to make the user reference more closely resemble a typical author attribution.