"Real detail master relationship" would be a case of entering invoice header and its multiple items and ability to show totals of these items values on a header or a footer of invoice and assigning these values to some fields of invoice and all of that on one master webform with a subform.
Without that, for me, PHPRAD has limited potential. If it is possible, please show us a concrete example.
This is a great idea. I am sure there would be many interested in this option. I would also be willing to assist in the testing and development process, primarily with my knowledge of Firebird SQL.