How to add materials to a Work Definition when no BOM exists

Summary:

HI,
In the Manage Work Definitions page, how can we add materials to a Work Definition when there is no BOM (item structure) for the finished item? Please provide the step-by-step procedure.
Note: We are using the classic (non-Redwood) UI for the Manage Work Definitions page.

Content (please ensure you mask any confidential information):

• We want to register operation materials directly on the Work Definition even though the BOM does not exist.
• We need prerequisites (roles, item setup), page navigation, and the exact fields to populate on the material line.
• We also want to understand if there are manufacturing parameters (e.g., synchronization between BOM and Work Definition) that could prevent adding non-BOM items, and how to configure them to allow this.