You have the ability to add groups or lists of recipients in your workflow when you have the need to communicate with larger bodies of people. You can choose at which point in the hierarchy of your workflow that individuals or groups of people are contacted. To do so, select your appropriate account and go to "Channel Management" located on the top right hand side of the screen. From here, click on the node at which level you would like the communication to occur, and select view. Here you are shown the option to add a contact person. Click on edit, and you will be presented with this:

From the dropdown box, choose whether you would like to add an individual or a group of people. To add a group to a node, you must have already created the group for your account, which you can find more information on here.
Select the individual/group you would like to communicate with, and then click save.

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