Grass Tool Parameter for Type on Instanced Materials?

Currently our project uses one master material for our terrain, and we will have approximately 9 different environment types that branch off of the master material as material instances. Everything works great until it comes time to change the grass tool type for each different environment.

All the environments will be using different types of default grass, with the major difference being the primary color of the grass. As it is right now, we are unable to use material instances from our master material because the type of grass that is applied to the grass tool is defined within the master material itself.

Is there any method that would allow us to define what type of grass is used within a material instance of our master material? It would be great if we could specify it directly within the material instance parameters without doing any sort of unusual rigging within the master material. I think the work around at this point might be to setup a series of multiple grass output nodes that we can turn on or off based on a series of switches that can be controlled as parameters?

Any help would be greatly appreciated, right now we are trying to keep this as simple as possible and if it involves diving deeper into the source programming we might be able to do that in the future, but this sort of option feels like it is something that would be very useful as a standard feature for the grass tool.