If you can find a way to get the “Contacts” feature enabled on your ST account, it is very simple to send either push or SMS notifications to specific users. I am not sure what the hold up is with general availability of the Contacts feature. It was available early on in the v2.0 ST App rollout last year on the Android platform. Then ST seemed to hide it from users who had never set it up. For those that did set it up, they still have access to it, and it seems to work very well for my purposes. There is a thread about a trick that you can use to get it enabled, if you have access to an Android device.
Here’s the thread…