Maintain an email group on iPad - no Mac involved
May I suggest our unique "MailShot Pro" app, which is the ONLY app on the store that lets you create contact groups in your address book that you can use from any app to send email, just as you would use a single contact.

We have tens of thousands of users using it for exactly the sort of thing you describe


You can protect privacy by adding the contact group to the Bcc line.
You can edit the group permanently in the MailShot app, or temporarily just before you send an email (simply by saving and retrieving the email from Drafts)
And you can share groups between multiple devices using iCloud contact sharing.


http://itunes.apple.com/us/app/mailshot-pro-group-email-done/id445996226?ls=1&amp;mt=8. (A free trial version is also available.)

Peter

Soluble Apps

Full Disclosure:I am the developer of MailShot and will benefit from its sale, but so might you :)