Hi,
The POI's are in xygrib_poi.ini.
A quick workaround to create groups would be keep each group in an individual xygrib_poi.ini_GROUP-A etc. You would have to copy the group needed to the config folder as xygrib_poi.ini.
Please backup all your ini files before trying this.
I will make a note of grouped POI's as a feature request to be added sometime downstream.
Thanks,
David