J.H.
If it is just you communicating to them, simply set up a group email and send out the information. And if the only response you need is RSVPs to activities, then Evite is a good addition to that.
If the other families need a way to contact the group too than Yahoo Groups would be a good way to go. You would need a Yahoo account to set it up, but you can use any email for it. Pretty much there is a group email address and anyone who sends a message to this email sends it to the whole group. As admin you would add peoples email addresses through a Yahoo account to make them members. There is a calendar function that can be used to send reminders to everyone.
Do NOT use the Yahoo Group email for an Evite. You need to input everyones individual emails into an Evite. If you use the Yahoo Group address for it there is only one "person" that will rsvp and anyone else would just be changing that response.
PM me if you need help. I set one up for my HS class years ago. Too bad they are against FB - that is by far the easiest way to go (I set one up for the group there too).