Is there a way to add multiple resources to the Organization at the same time?

Summary: As I understand there is a pre-requisite to adding users in a Contract. Any user who needs any kind of access to Contracts would need to be defined as a resource in the organization.

Is there a way through which multiple users can define resources in the organization through a spreadsheet upload?

The Client has hundreds of users who need access to Contracts or need to be assigned a Contact in a Contract. So please suggest if there is a mass upload facility for this resource identification task.

Content (required): As I understand there is a pre-requisite to adding users in a Contract. Any user who needs any kind of access to Contracts would need to be defined as a resource in the organization.