Hello,
The current CI360 Connector and External System Task (EST) architecture is not designed to pass (or chain) the responses to the next EST, especially not authentication information.
In your case, I believe building a custom third connector endpoint will be more suitable. In this new API, you will call and obtain the authentication token, and then make the call to the actual API.
In your EST, you will configure the new third endpoint. For the security of this new endpoint, you can consider a long-lived JWT or any other authentication method supported by CI360.
Link for supported authentication: https://go.documentation.sas.com/doc/en/cintcdc/production.a/cintag/endpoint-details.htm
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