What is the fastest way to combine two xml files into one

Question

If I have two string of xml1 and xml2 which both represent xml in the same format. What is the fastest way to combine these together? The format is not important, but I ju

Answer 1

Best solution to me, based on Jose Basilio answer, slightly modified,

var combinedUnique = xml1.Descendants()
    .Union(xml2.Descendants());
combinedUnique.First().Save(#fullName)