In opentaps CRM2, you can have several contacts who are assigned to a task and one contact who is responsible for the task at any time.
You can change who’s assigned to the task and who’s responsible for it in the mobile app or web UI. There are also a couple of shortcut ways:
1. You can put a list of users, each with their @username, after the task description when you first create the task. All these users will be assigned to the task, and the first user will be responsible for it. For example, you can create a task “New Task @jane @bob @sue” In this case, Jane, Bob, and Sue will all be assigned to the task.
2. When you get an email notification of your task, you can reply with [assign @usernames] like above, and it will also change the assignees list and the responsible person of the task.