I've seen a lot of similar questions, but not exactly this scenario.
We believe we're following the right guidelines by only estimating time in a Story's sub-tasks, and using the built-in rollup functionality to show all the work remaining for a Story.
However, once we set a Story in motion, it's possible that more subtasks could be discovered, and we'll add them to the story.
The issue is that adding these subtasks, with their time estimates, increases the original estimate roll-up of the parent story. So we aren't shown intuitively that the parent's estimate increased from its original value. Presumably it will show as a bump in that sprint's burndown, but not when looking at the story card itself. It looks like the estimate was always at that higher number.
This is a bit different than having your Original estimate for an item, logging work to it, and also saying that now I think there's more work left than originally estimated. That will show nicely in the Time Tracking bars for the individual item; the Remaining will creep out past the Original.
What I'm asking is, is there a way to "lock" the Original Estimate of a parent story, so that when a new sub-task is added to that story, its estimates only impact the Remaining values of the parent story. The Original Estimate should stay the same, so that it's clear that more work was discovered than originally estimated,
