Attaching Cookies with HTTP Client GET/POST

I'm dealing with a web service that allows Basic authentication. Once authenticated, the authorization header can be omitted on subsequent requests and replaced with a cookie returned from the first request.

As per the description on these operations, if i set useCookies to true, I can see the cookie is passed between different steps when all contained on the same flow.
However, I am looking to generalise this flow and break it down in to sub flows, when I do that the cookie from the parent flow is no longer passed to subsequent calls in child flows.

Is there anyway to pass the cookie via the HTTP Client operations or will I need to resned the authorization header each time?

Thanks
Sunts