Hi again @StephenOTT.
I 've read thoroughly your link post forum here (Pattern Review: DMN Looping for Array Input) but my process scenario differs a bit from your example in the fact that I don’t have to match multiple things to multiple users (Systems to users) as yours.
In my process scenario, I 've generated an array of users (“administrators”) in the Script task with javascript and I 've also created a JSON Array (“item”) in my 1st task form (“Configure specifications & items”) with camForm function. By this way, only 1 instance of the task (“Select items”) can be automatically assigned to each user (which is the desired in my case) but my problem starts after the completion of the Multi-Instance Task because I can’t keep and transfer the json values from all the completed instances but only from the last completed one.
Process engine substitutes each time the json values on the completion of each instance of the task. 
Has anyone got any idea on this please?
A screenshot of my process:
Thank you,
Steve