To send an SMS to a guest added to the guest list at a later stage, do the following.
- From the dashboard, click on SMS and Email and Select New SMS
 

- Make sure the Recipients Field is set to None.
 - Then add the names of the guests recently added (make sure the guests have been added). To add a new guest, simply click on the blue plus sign below the Additional Recipients field.
 - Enter your message and click on Send.
 
The message will now be sent to the recently added guest.