To stop inheriting headers/footers from the site theme, update the Body script of the group theme and update the calls to $context_v2_themeBody.RenderHeader() and $context_v2_themeBody.RenderFooter() to set the option InheritContentFromParentDepth to 0 (it defaults to 10 and causes parent content to be inherited).
To stop inheriting site theme styling and scripts, set the similar option, InheritFromParentDepth, to 0 when calling $context_v2_themeHeader.RenderStylesheetFiles() and $context_v2_themeHeader.RenderJavascriptFiles() and/or remove the call to $context_v2_themeHeader.RenderParentHeader().
