A family of Microsoft relational database management systems designed for ease of use.
Hi David,
It's not feasible to assign a task to multiple users. If we need to assign something to more than one person, we may consider adding another task with a similar name, and assigning that task to the other person. See Assign people to tasks.
We welcome you to vote for this feature in the following link in uservoice. Actually, from the admin responses in the link, we can find that this feature in under development now:
Assign tasks to multiple users
Regards,
James