Google Groups

Add new members

1. Go to Google groups homepage, log in with your Google account and in My Groups go to the corresponding group page
2. On the right hand side there is a menu in grey letters. Click in Manage
3. Within Manage, on the left-hand sidebar there is a Members menu with sub-menus to Add, Invite, etc. new members

One can only invite a certain number of email addresses at a time, I think by batches of 10 emails-people.