2 risposte
A task can only be assigned to one person. The multiple user feature, which it sounds like you're familiar with, creates multiple records. There is an idea out there to assign a task to a queue, which might work for what you're looking for if it should get delivered.
https://success.salesforce.com/ideaview?id=087300000007HC0AAM
In the meantime, I don't think you could close all tasks without building out something custom. Like a flow that looks for all tasks linked to the same record with the same subject and closes them. I don't love that because if someone changes a subject, things will slip through the cracks.