Transfer Area to a Shared Parameter from Filled Region

Hello all,
I’m trying to work out Desing Flows (for Stormwater Design) for different surface areas or roofs. I have created Shared Parameters for Rain Intensity and Soil Permeability coefficients, and I’d like to be able to extract the Area from different Filled Regions as a Shared Parameter as well.
If I could get the Area out, I could then use it in a Tag Family and obtain the above (bear in mind that Desing Flow = Rain Intensity x Soil Permeability x Area).

Any help would be much appreciated!

Thanks!

Did you try searching the forums? These seems like a good starting point: Write filled region area parameter to custom parameter for selected filled region types

I feel like using area plans would be a better fit here as it would live update allowing you to calculate the result without having to run the graph.