Assigning a project to multiple users

I have created an app for tracking projects. Some projects will have multiple people assigned to a single project. Is there a way to assign a project to a group of people? It's not practical to go through each account and assign the project to each person. I have tried to place all the desired accounts into a "User Roles" but when I place that Connected Field in a form it simply gives me a choice of all those Users in that group.

Thanks in advance!