What is the most vital piece of information when manually adding a traveler to a group?

The most critical piece of information when manually adding a traveler to a group is the traveler's Social Security number. This identifier is essential for various reasons, including ensuring accurate tracking of the traveler's records, managing financial transactions, and maintaining compliance with regulations that may require personal identification validation. The Social Security number serves as a unique identifier that helps differentiate between travelers who may have similar names or other personal details.

In contrast, while a traveler's birth date can help verify their identity, it is not as unique or secure as a Social Security number. The department name, while useful for organizational purposes, does not play a significant role in the actual mechanics of adding a traveler or ensuring compliance. The travel request approval status is also important for administrative processes but does not provide the same level of identification needed when officially integrating a traveler into a group. Thus, the Social Security number stands out as the most vital element for this specific task.