Calculate the time taken for each employee on three different columns for the same SFC

[alespooletto]

I have a bit of a difficult situation at hand. I have SFCs which are worked in specific work centers, for each work center an employee is assigned. 

Then, each work center has different modules, maybe 2, 3 or 4 that could be completed each in their own sepcific time. The time is assigned as the difference between:

Max({<ACTION_CODE={'LABOR_OFF'}>}DateTime) - Min({<ACTION_CODE={'LABOR_ON'}>}DateTime)

And until here, everything is fine. Because until now it's only one product taken into account. But, for each SFC, there are AT LEAST one item between "PrimoRiduttore", "SecondoRiduttore" and "Motore". 

So, an SFC can be composed by minimum of 1 and maximum of 3 different items. But these items are all worked in separate work centers and by different users (usually). Right now, I am taking into consideration only the time for the work center, so whichever item was made I wouldn't really care, because the duration would still be correct. But when I visualize this, I have no idea how to refer the user to the specific item they made

AKA I don't know how to make it so that, in the table, I could only see who worked on which item. 

I am going to show you the data model as well, so it could be better understood. 

So, to be able to associate a worker only to the specific item they worked on, I would like to have some help if possible. If need more information, please let me know. 

Thank you