Hello @SamWhitehouse,
You can write Javascript to Dynamically load IFrame using below Javascript in Model Driven app
function OnLoad()
{
//Get memberid
var value = Xrm.Page.getAttribute("new_memberid").getValue();
//Get the default URL for the IFRAME, which includes the
// query string parameters
var IFrame = Xrm.Page.ui.controls.get("IFRAME_NAMEofIFRAME");
var Url = IFrame.getSrc();
//Append the parameters to the new page URL
newTarget = value;
// Use the setSrc method so that the IFRAME uses the
// new page with the existing parameters
IFrame.setSrc(newTarget);
}
Hope this helps. Let me know if you need more help.
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