Both use single sign-on. When viewing tasks in Rational Synergy, if you want more information about a change request that drove the task, you can find out easily. Right-click over the change request and choose Properties. Rational Change opens and shows the details of the change request.
To require that a task is associated to a change request before it can be completed, enter the pseudo-attribute "change_request" as a line in the required_attributes attribute.