The idea would be to be able to better handle byproducts.
Here it would be nice to add recipes linked to a particular byproduct, like you can add the main products, to further process those. They would act like other processing steps, except they scaled with the input, instead of the output.
This would truly come into its own with recipe loops added by some mod packs, where currently it is really fiddly to for example balance a lossy recycling recipe with a second one that generates the same thing from scratch.
With this you could simply add the recycling recipe linked to the byproduct, converting 100% of it, while then adding the second recipe that produces whatever else is necessary, instead of fiddling with the production percentages to try get the byproduct close to 0.
