Estimate at Parent Story, Log work at Sub-task

From a project management perspective the way our team works is that we estimate at the Story level and then have the developers creates sub-tasks and log their work at the sub-task level. The issue we have is that the time logged against the sub-task does not reduce the remaining estimate we did at the Story level. This allows us to do a top-down style of estimation. If there could be an option to allow you to select where you want your time rolled up to, or have a preference on how time tracking works, it would be appreciated.

Example:

• Story is estimated at 16 hours
• Several sub-tasks are created with no estimations
• 4 hours worth of work is done against a sub-task
• Remaining time left on Story to be 12 hours