Mutipleuser field people to receive email notification when entered

[Andrena]

I only want to send one email notification to people I enter into the MultipleUser field. I may do this upon creation, but most likely it will be somewhere along the many workflow statuses. Is it possible to send an email notification to the person when they are added to the MultipleUser field?

Thanks

[QuentinB]

Hello, In a notification scheme you can associate an event with a Groupcustom field value.
This could fulfil your need 

[Andrena]

I tried that. What event would I associate to notify the person when they are placed in the MultipleUser field? "Issue Assigned" merely notifies them when the Assignee field is changed not when MultipleUser field is changed.