You can leverage HubSpot's flexibility to integrate data from other systems into it, even if the data doesn't fit HubSpot's default properties. To do this, you can create a custom contact property using the HubSpot API and Python. First, you need to get set up with the HubSpot API and Python by connecting to the API with your API key and installing the necessary libraries. Next, you check if the property already exists in the HubSpot web interface or through the API. If it doesn't exist, you create a new custom contact property using the API or web interface. Once the property is created, you can update its value by identifying the contact's id and writing data to the custom property. Finally, some general advice on the HubSpot API includes implementing error handling for rate limits and daily API usage.