Before the most recent update we were able to send a message to multiple numbers (20 +) and it would individually send to each number. After this new update, we are only able to send a group message to a max of 10 people and it puts them all together in the same group.
We've raised this to our Product Team. This feature is available with the new RingCentral App. You can try the beta by logging in to this website https://app.ringcentral.com/. This new app will be launched soon this week for you to be able to install it on your computer as well.