How to add markers or tracers on top of colormap plot by using Qcustomplot?

Question

I have an ongoing waterfall colormap plot. I want to add multiple tracers/markers on top of the colormap plot, so that they can indicate some sort of trajectory on the colormap plot. I have a function that keep feeding me those tracers' coordinates. How do I put them on top of the colormap plot?

I have tried QCPItemTracer, but it can only plot one trace at time. Are there any other options?