In waterfall graph where there is a stacked bar, while using the label i have some specific client request

in the below snapshot

The requirement is like the

1) The label size should be 10.

2) When the label is in centre ,for the green bar (performance based payment) ,if the bar is too lean , then label will go outside(pic 1)

3)When the label is in top, in the stacked bar volume discount will be inside base discount bar,which is not acceptable as it is confusing (pic 2)

4)Automatic or on selection is not acceptable,

5)But the label should be clearly visible

Is there any solution? or any work arounds? Please respond