Within SMMware, the first approach is called “direct” adding of attendees. When the event owner creates the event and choose the direct add type, they see a list of associates and click on the checkbox per associate to attend.
Attendees will receive emails informing them of their assignment. Any revisions to start and end dates or event details will cause emails to be sent to all attendees. If the event definition stays the same, any changes in attendees results in emails to just those affected. Anyone added or removed receives emails.