@P, Pioline (Cognizant) The Patient-everything operation in Azure Health Data Services - FHIR service should fetch all resources related to a specific patient, including claim records that reference the Patient ID.
In your case, if the claim resource ‘xyz’ is related to the patient ‘abc’ it should be included in the response of the Patient-everything operation.
If you were not able to get the Claim resource 'xyz' in the response during your test operation, it's possible that there is an issue with the implementation or configuration of your system. I would recommend reviewing the documentation and specifications for the Patient-everything operation and the relationship between the Patient and Claim resources in your system to see if there are any issues or discrepancies.
let me know incase of further queries, I would be happy to assist you.