Hello April!
I believe the only way you can do this is with a Send Email Plug-In. If I remember right, you would see the other "To" people in the email. Someone else please correct me if I am wrong.
The downfall to this is maintaining the people. Plug-Ins are not as dynamic as you have to revise the solution to update, unlike swimlane/SharePoint groups. Also, you need to consider if you want those getting the email to be able to reply to all and take communications, and the work, around the purpose of the workflow.
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Scott Gorski
General Mills | Advanced Analyst, Master Data Management
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