Maybe in future releases of Nintex, there can be an out-of-the-box easy solution to capture the delegated user.
In Nintex workflow I'm looking to add the delegated user in an approval workflow to a column in the SharePoint List I researched this and found that I needed to run a parallel process with a run if loop, manipulate xml from the Nintex web service.
Maybe in future releases, this can be out -of the box.
senthilselvi Murugesan commented
Any updates on this? We really need to capture the delegation details like who delegated to whome and comments.