How to populate multiple assignees into a ticket


I'm trying to be able to enter more than one assignee for an interaction ticket, and have it send out the appropriate information to both assignees. 

I added the new field as an array, and was able to enter an assignee but only that one. When I click on the populate button on the field below the one that already has an assignee it looks like it thinks but doesn't do anything.

I've attached pictures of my form and database field.