Create Union command is part of Cluster Placement. I do not know what bundle of suite license you have.
To create a union, you need to select at list two parts. After you select them, from RMB select Create Union. While both of this parts are still selected, RMB and select Create Like Unions.
Thank you for answering my newbie questions!
My license did NOT have that feature activated. I"m going to see if I can get management to add it.