Hello Stuart, if I understand you well, your need from Custom Query resource to create expandable tree, or just displaying of the parent entity only once. AFAIK this is at other places in Node Management, etc. it's done by the JavaScript. The Custom query resource everytime gives you the table of results defined by the query. I'd wonder if something like this was even possible in SQL. However there should be possible to achieve it by using the Old Report Writer, make report for the info you need (similar principle to e.g. canned report All Disk Volumes) and add it to your website inside the "Report from Report Writer" resource. In upcoming release there should be also possibility to add the "Custom Table", as known from the Web-based reporting, to the view, which also should do the trick for you.
Regards,
Honza