You can send a chat to any of your contacts who also use Message+. If they don’t have a data connection, your chat will be sent as a text or picture message.
How do I start a Group chat?
To start a Group chat, open the app, press the + sign and select the group chat icon. Choose a group chat topic and select the contacts you’d like to add to the group. Everyone will need Message + and be on Wi-Fi or mobile data.
Alternatively you send the message to each person as a text; however this isn’t available on iPhone.