Hi Doug – The Group Announcements text box is made possible with the BP Group Announcements plugin that comes with CBOX. (https://commonsinabox.org/documentation/plugins/bp-group-announcements).
You might want to open up an issue here – https://github.com/cuny-academic-commons/bp-group-announcements/issues – so that the plugin authors are aware of the need.
It sounds like it might be a fairly straightforward change.
(If you are savvy with the way plugins work – you could do the coding yourself and then create a Git pull request and the team can look look at your enhancement and merge into the plugin’s code.)