Any idea how to loop and add all the value to the attribute of the xml node?

I am working on a batch flattening project using Watched Folder.

I have a parent process for locating the directory and invokes a subprocess for flattening the PDF files.

I want to write the failed directory to the XML.

If there are multiple failed directory locations and if I want to add it to the node, it won't let me do.

If I set the Xpath location as /process_data/outputXML/flattenDirectoryRequestMessage/failureFileLocation[x]/@path it gives me invalid character exception.I am using 'x' for looping and incrementing.

If I don't use the [x]. The directory is overwritten.

Any idea how to loop and add all the failed directories to the attribute of the xml node?