Streaming (x,y) and (x,z)

I have a stream up and running with my own API for dlang.

I’m doing my own “running mean” calculations on the y value, and feeding it to the stream as the z value for each post. The data is successfully pushed to the stream, but it’s obviously not showing because it doesn’t know what array to associate with (x,y) & (x,z).

How do I define this as a separate trace without having to create a new plot? I don’t understand why the data is read-only (telling me to find the non-existing grid) when I want to define the traces, I’d be nice to be able to set these things in the GUI for the current stream-plot I’m working on.

I realize I can make another stream token for this problem, but it makes little sense to double it up when the data is already being pushed by the main stream?