There's the same issue in the Pyanodon's mods where you have different producers of stone by-product. Currently I have 6 stations providing it, 5 ore by-product ones, and one backup from regular stone mine.
I would like to be able to prioritize them and avoid needing large, specialised and high-throughput stone-terminal that will accept stone from all of these stations, prioritise locally and then provide it at centralised provider station.
Another use-case for something like that would be fuel stations, there're dozens of burnable fluids, all of these could be used as fuel before they're voided locally on overflow, I would like to have them prioritised so for example: first goes Gasoline, then Syngas, then Kerosene, then Coal gas, then Tar, and so on.
Above would require some clever mod feature that allows us to define fluids for some virtual fluid and replacing conditions whenever needed.
Example: We have a provider station that provides 1000 Gasoline and we have a requester station requesting 1000 FF (fluid fuel virtual signal of some kind), we check some user-set mapping for this FF, search for any station providing mapped fluids ordered by priority, pick the first one and dispatch a train that goes to the provider station with an appropriate order. This might be also used for solid fuels. Another approach might be to just use full cargo inventory for these but that would break the mod's thresholds feature.
