If you enable worksharing, your links are contained in worksets.
If you update a linked file and want to reload the link, the workset in which the link is located must be editable. If it is not, an error message appears indicating that the link could not be updated because of the workset's non-editable status. See Make Worksets Editable.
It is good practice to assign a team member to track links and be sure the appropriate worksets are editable. After updating the link, the team member should synchronize with central so that all team members have the updated link. See About Saving Workshared Files.
Also, you may want to create a workset exclusively for links, so that workflow is not interrupted. See Setting Up and Managing Worksets.
For worksharing-enabled models, when in a local file, you can use the "UnloadFor me" command to unload a linked Revit model for the current user only. This command works like a permanent override and remains set for the user, for that link, until cleared with the "Clear my override" command. The setting is stored in the central model, per user for each RVT link. This command allows you to keep Revit links unloaded for portions of the model you aren't working on, without affecting other team members. See Tools to Manage Links.