Charts - Stacked Bar Charts - Change order of stack

We made a report that uses the Stacked Bar chart feature to try and layout how long each project mile stone takes in comparison with all of the other milestones (Picture attached).

These are stacked by MileStones, but the milestones are not in the order that we want them to be and there's no way to change the order. The milestones should be in the same order as the MileStone path that is setup.

The easiest fix that we can think of is that the chart should allow us to choose a sort order for the chart fields.

Workaround (we think), make a custom field that Concatenates Mile Stone Sequence with the name of the Mile Stone. It'd be "1"+" Mile Stone Name One"