1.
Select Help > Sample Data Library and open Consumer Prices.jmp.
2.
Click the green triangle next to the Split into Series script.
3.
Select Graph > Graph Builder.
4.
Select Date and drag it to the X zone.
5.
Select Apples, Bananas, and Bread and drag them to the Y zone.
Area Plot for Apples, Bananas, and Bread by Date
Because banana prices are uniformly smaller than prices for apples and bread, the layer for Bananas is at first entirely hidden behind the other two layers. The apples price is hidden behind the bread price for some months. Use the Line element to see prices for all three clearly.
Overlaid Area Style
9.
In the Area options, click the triangle next to Variables. Select Y Bananas so that it is highlighted, and click the down arrow once.
Note: When selecting Y Bananas, be sure to leave the check box marked. Otherwise, the variable is removed from the graph.
10.
In the Line options, click the triangle next to Variables. Select Y Bananas so that it is highlighted, and click the down arrow once.
Overlaid Area Showing All Layers

Help created on 9/19/2017