When tickets are added (or removed) in the middle of an iteration, the change should show up on the charts on the day it was made. Right now, the story points are changed on the first day in the chart.

For example, say a sprint started on April 1 with 50 points. Suppose a 3-point story is closed on April 2 and a 5-point story is added on April 3. The story point burndown should show the following:
April 1 - 50 points
April 2 - 47 points
April 3 - 52 points

Right now the above example results in the following chart:
April 1 - 55 points
April 2 - 52 points
April 3 - 52 points

This doesn't reflect reality! Based on standard scrum principles, You should be able to change the burndown for days in the past.

The Issue Burndown Chart should also work this way.