I don't have specific information about whether tracking numbers on Facebook Marketplace can be changed. However, in general, once a tracking number is provided, it is typically associated with a specific shipment and can't be easily changed to a different number.

If you need to update or change a tracking number, your best course of action is to directly contact the seller or the customer support provided by Facebook Marketplace. They may be able to assist you with any necessary changes or updates to the tracking information.

Keep in mind that policies and features on platforms like Facebook Marketplace can change over time, so it's advisable to check the most recent help documentation or contact Facebook Marketplace support for the most accurate and up-to-date information.