Third parties want to integrate and reuse data about me to provide me with a service
Third parties are interested in integrating and reusing (and potentially adding new data to) your existing data for a new purpose unrelated to its original capture.
Sometimes they may wish to “add value” to existing data – to have a better way of doing photo analytics to identify and categorise objects in your photos, for example, or a new way of analysing your heart rate to detect medical conditions. So a personal health service provider might wish to use your medical record and your fitness sensing device to build a new kind of exercise monitoring service. Or a budget support manager might wish to integrate your financial data with your budget goals to create a new service for you.
They have a newly formed second-order relationship with you based on the new data they have produced, or the value they have added to your existing data. But they are a third party in respect to the existing data about you that was co-produced between you and other providers.