What algorithm-family or problem-space description fits? Industrial process feeding ingredients to process

Our process continuously feeds (normally <= 8) ingredients from a choice of hundreds, using 3 feeders only. So if ingredient count X is > 3, 3 through X are stirred together in a batch process and the resulting "premix" gets put in its own feeder. 6 is a hard limit for the number of ingredients a premix can have. It is possible to need to make 2 or even 3 premixes so that 2 or all 3 feeders feed premix. Unlikely but possible. This process is for experiments where we try 2 to 15 different recipes where we vary the ingredients and/or the weight-proportions. Hopefully this image conveys the situation. A person is deciding what ingredients get their own feeder, what goes in the premix, what experimental runs have enough in common to share a big premix, and what order to do the runs in to minimize changes. I'd like to make Excel and VBA make all those decisions for her. I can code it up once I get my mind around the problem. I can even derive a symbolic system to describe it, but I'm sure someone smarter than me already has. However I don't know what family of problems this is from. Not knapsack, imho. Can you point me in the right direction?