Its possible to stack plots using a WaveForm Chart:

You can also do it using Mixed Signal Graphs.
But the functionality is very restrictive. I propose these improvements:
- Allow stacking plots on Waveform Graphs and XY Graphs also.
- Allow users to modify the number of stacked plots at run-time. This is currently impossible. You need to pick the number of plots you want to stack during design-time. And then you are stuck with it at run-time. Though there are certainly plenty of clumsy attempted workarounds to this problem (e.g. see here). It would be great to have this function for run-time. Its very common in Biomedical data-acquisition applications to allow users to vizualize data in stacked plots (EEG for example), and its a pain to program this in a flexible manner using LabVIEW.
http://www.medicollector.com