Hello,
DPC does not currently attribute patients to providers based on CMS MSSP ACO relationships. However, have you explored our sister program, the Beneficiary Claims Data API (BCDA)?
The claims data delivered by DPC and BCDA are in the same bulk FHIR format, but BCDA is designed specifically to support and deliver claims for CMS MSSP ACOs and their assignable or prospectively assigned beneficiaries.
I suggest checking out their website for more information on how to get started: https://bcda.cms.gov/. If you have further questions about BCDA, you can post to their Google Group: https://groups.google.com/forum/#!forum/bc-api.