IBM Instana documents the merge logic of custom payloads for alerts and global configurations very clearly. The rule states: "If the same key is defined in both a global custom payload and an alert-specific payload, the value from the alert-specific payload will override the global value for that key." This ensures alert context management is precise, enabling targeted incident response with the most relevant and high-priority data. There is no concatenation, and no alert cancellation or error is triggered as Instana resolves key collisions silently by giving precedence to the more granular, context-specific setting (alert-level). This verified behavior guarantees custom alert events always contain relevant payloads, supporting accurate automated remediation or escalation.