TreeView Prevent Dragging into Children

Hi there! I’m using a TreeView to display some data similar to folders containing different files. The thing is, I want the folders and the files in the folders to be reorderable and I want the ability to drag files from folder to folder, which TreeView fully supports. However, I want to prevent the user from dragging a file into another file (i.e. I want to prevent nesting at that level). How would I go about doing this? Thank you!