Is it possible to use the BuildRowset function and have a descending order for a single attribute in the feed? If we get 4 records with 4 different time stamps for each, we'd like to sort them by earliest to latest.
Sorting XML with an XPATH is easier to do with XPATH 2.0, but SFMC only supports XPATH 1.0.
This may be an option for you: Have SFMC Support enable Script Activities for Automation Studio. Write a script that retrieves your XML and writes it to a Data Extension. In your email, use the LookupOrderedRows() function to retrieve the data in the desired order.