Hi Richard,
I suppose you want to utilize the group box collapse/expand functionality?
If so, then you might try some other ‘tricks’, for instance; you can try modeling a similar UI functionality with some on change microflows in combination with conditional visibility. Also I've seen similar cases in which people used CSS to show/hide content of a list view item, so that the list view item itself becomes collabsible. Maybe that's something you could look into?