Excel Bubble Chart with Upper & Lower bounds

Hi all,
Here's my problem:
- I'm making bubble chart to see the impact of forecast on TO performance:

• X-Axis: TO Change
• Y-Axis: Forecast bias (%)
• Size: TO Value

- I want to add in one more criteria, which is the upper & lower bound for forecast bias:

• -2.5% to +2.5% is the bound where the forecast bias should be. Forecast bias higher or lower than this bound needs to investigate
• Every categories with TO decrease while forecast bias is within range (-2.5+2.5%) is considered bad performance

I want to highlight these upper & lower bound with area colored (like below pictures)
bubble chart example.png
Is there anyway to make this automatically in bubble chart?
One of my thought is to make another chart behind this with the selected criteria. the problems is the axis is not matching with each other & it is troublesome to change when the data change

Could you help me with any better solution?
Thank you