The Area element in Graph Builder can stack filled areas, but you'll need to get the proportions first. They can be computed from Distribution, though it takes a few steps.
You can recreate the Oneway density curves in the Distribution platform by using Red Triangle Menu > Continuous Fit > Smooth Curve. There you can adjust the smoothing parameter and you can click the smoother's Red Triangle Menu and choose Save Density Formula to create a formula column. Since you're planning to panel the output, you should use a BY variable when you launch distribution and it will be accounted for in the saved formula column.
Being a nonparametric fit, the formula is enormous.
Once you have the formula, you can create a new data table with an artificial grid of input values (Right-click > Fill and Column Info > Initialize Data are handy), copy in the formula to get the smooth response column, and then make another formula to turn those into proportions. Finally, you can plot the proportions in Graph Builder with the Area element.
I tried with Big Class to see proportions of M/F over the ages that had more than two rows of each (12 - 15). Here's by grid table:
Density holds the formula from the smooth curve fit, and Proportion is the new formula, the ratio of the density and the sum with its neighbor.
Using the Area element in Graph Builder, you can panel by Age and overlay by Sex to get:
