Pallete RAG, with no Amber

[Robl]

Hi,

I have a stacked bar chart nested into a repeater table.
The series of the chart is 3 separate items, based on DMR calculated members.
One member for Green, one for Amber, one for Red.

Sometimes one of the members is empty.
Is there a simple way to make each series display a specific colour?
Regular palette won't work as the missing values cause the colours to be displayed on the wrong section.

I can't find a conditional palette that works correctly over the three separate series items.
If the series was one item with three values then the conditional format should be quite easy, but it isn't.

There may be a prize for whoever can help me.*


*there may also not be.