Build an extended Grafana Heatmap Plugin with Line and Scatter Overlays

We are using Grafana to visualise some of our data. We need help authoring a visualisation plugin that doesn't appear to be available. We need to be able to produce a heatmap - just like the built-in Heatmap plugin, which could be copied as a base - with the addition of either a line graph, or a scatter plot, which will be drawn OVER THE TOP of the heat map. As the heatmap is drawn using SVG, this should hopefully not be overly complicated - we are hoping to simply add some additional content at the end of the heatmap SVG output. The line/scatter-plot will use the same axes as the heatmap. Options are limited - apart from which channel(s) to get the line/scatter data from, only really thickness and colour of the line/scatter are needed. The scatter data is only 2D - you don't need to colour/size or otherwise change the scatter symbols based on a value - each is the same colour and same size.