Even with non unique ids enabled you should be able to apply different icons to the same items?
For the "copy" of the same items you would need to enable ZOs unique IDs then, right, as they are really unique. But this is somehow troublung for all other items imho as you would need to re mark all items you had collected already. This is very annoying.
Else the FCOIS custom unique ids would be the way to go in order to distinguish them by e.g. "who crafted the item". But it's still not making any difference then to "who will use this item" and what marker icon is applied to it.
You should maybe use FCOIS character settings then instead of the account wide settings + normal itemInstanceIds (non unique)? This way you are able to distinguish the same items at your different toons with different icons. But this would include all other settings. And you could keep the non unique ones.
As you usecase seems to be a special one, or at least I never saw someone researching all with all toons
, this might be needed here though.
You can use FCOIS automatic markings -> research wich integrates CraftStore e.g. to mark your researchable items based on the CS and FCOIS settings! Read the tooltips at all the automatic marks->research settings within FCOIS please, they describe how it works/how they behave with the other addon's settings.
You are able to use ESO standard research markers for the logged in char, ResearchAssistant or CraftStore there. Afai rember CraftStore would be the only supported addon to be able to check for other not-logged in toons, depending on if you have NOT set a main crafter at the CS UI (right clicking a character name at the CS UI toons list -> a star icon is set to the main crafter then).
if you set a main carfter only this one will be checked.
Not sure anymore how exactly it works, the tooltips should be actual though ;-)