Just to make sure I’m understanding this…
Area Scheme 1 has 3 Areas (A, B, and C.)
You want to get the Total Scheme Area by summing the individual areas of Area A, Area B, and Area C.
You want to apply this Total Scheme Area to each Area (A, B, and C) in a parameter.
As @JacobSmall stated, you just need to repeat the total area value for each area or use levels to correctly map to the proper element.