Capture Legal Issues, Then Delegate
While your question about copyright is largely off-topic, and can't be properly answered on a site about project management, knowing how to deal with legal issues is certainly a project management topic.
From a project management perspective, making legal decisions is out of scope other than as a tracking item for the project. Typically, legal issues such as contract language, or business questions about property ownership, would be captured in the charter, project plan, or other documents as work items and then delegated to a responsible person for further action.
More broadly, if your company has not defined a standing policy about what documents or deliverables a client should typically receive during an engagement, then business leaders or the legal department should be involved in reviewing anything where there's a potential impact to the company.
Information Controls in Project Management
Disclaimer: Specific legal advice is something you ask a lawyer, not strangers on the Internet.
Copyright, and intellectual property (IP) in general, are complex areas of the law. In Canada, for example, there is a default assignment of moral rights in a work that is separate from economic rights. In contrast, the United States doesn't explicitly provide for moral rights, and many businesses address the economic rights through work-for-hire and non-disclosure agreements.
From a project management perspective, your company should have policies and standards about:
- employment, contracting, and confidentiality agreements
- information classification
- trade secrets
- company property, including IP
Your job as a project management professional is to include those policies and standards in your project planning, or to refer them back to the business if questions arise during the project. For example, your project controls may include gathering any necessary contracts or client agreements as a project dependency to beginning work.
Furthermore, your definition of done should adhere to any company policies for confidentiality and information classification. That may mean marking deliverables with the appropriate classification, or enforcing other controls as part of the delivery process.
If no policies, standards, or controls for any of these things exist in your company, it's not the project manager's job to invent them. Instead, you should document the issues, and raise them to stakeholders and business leadership for disposition.