Use data merge within XML driven content

Yes, I was able to do it that way. Thank you for the valuable input! Here is a dummy script that relinks the data files and adds a datamerge tag where the word "giftcode" appears. I will improve it for my application but as a proof of concept it works like a charm.

#target indesign

var doc = app.activeDocument;
var currentPath = doc.filePath;

var xmlFile = new File(currentPath+"/"+"design-data.xml");
var csvFile = new File(currentPath+"/"+"code-data.csv");

var links = doc.links;
var pages = doc.pages;

var searchTag = "giftcode";

for(var i=0; i<links.length; i++) {
	var link = links[i];
	// cannot use the built-in .linkType property because ID incorrectly lists csv as xml
	var linkName = link.name;
	var linkType = linkName.split('.').pop();
	if (linkType == "xml") {
		link.relink(xmlFile);
	}
	if (linkType == "csv") {
		link.relink(csvFile);
	}
}

for(var i=0; i<pages.length; i++) {
	var textFrames = pages[i].textFrames;
	for(var j=0; j<textFrames.length; j++) {
		var textContents = textFrames[j].texts[0].contents;
		var searchPosition = textContents.search(searchTag);
		if(searchPosition != -1) {
			var story = textFrames[j].parentStory;
			var dataMergeFields = doc.dataMergeProperties.dataMergeFields;
			for(var k=0; k<dataMergeFields.length; k++) {
				if(dataMergeFields[k].fieldName == searchTag) {
					doc.dataMergeTextPlaceholders.add(story,searchPosition,dataMergeFields[k]);
				}
			}
		}
	}
}



var pdfFile = new File(currentPath+"/"+"export.pdf");

doc.dataMergeProperties.exportFile(pdfFile);