When it comes to conducting an open house, one risk that may affect the vendors is the potential for theft or damage to their property. To prevent this, a control measure could be to have the vendor or their agent keep a close eye on the attendees during the open house. They can also limit access to certain areas of the property or lock away valuable items. Additionally, having a sign-in sheet for attendees can help track who visited the property. These measures can help ensure the safety and security of the vendor's belongings during the open house.