Retaining Data Point Colors while Deleting a previously plotted Column?

I cannot determine how to keep the data point color associated with a
particular cell in a series from moving. The problem has only occured
as I began going past 12 months of data, under a 12 month rolling data
format. This is the first month that we have more than 12 months, so I
delete the Sept 02 column and add a Sept 03 column.

For some reason, Excel shifts all the previously defined data point
colors to the right by one data point (actually, the data point values
seem to move to the left one position (desired), while the colors stay
in place (undesired). If I could use absolute references in the data
series, I may be able to retain the color. But Excel doesn't allow
that.

I tried keeping the Sep 02 data in the series, but empty, and this
retains the color/data point positions, but leaves a gap at the
beginning of the chart.

Also, this is a large report with 50 charts, and there are multiple
similar reports done monthly. So, all told about 250 charts. Using
the Conditional Formatting for Charts trick would be too much of a
task for me to set up on so many charts.

Does anyone know a fix or work around/trick for this?

Thank you,

Ken Black