Playlist Merge

Select any number of playlists and right click and select Playlist tools ➡ Merge to combine multiple playlists into one new playlist.

All tracks from all selected playlists will be combined into one new playlist. Any duplicates will be dropped from the new merged playlist.

Hotkey

You can set a hotkey for Merge in the Lexicon settings under Hotkeys ➡ Playlists. It merges the playlists selected in the playlist tree, so select at least two playlists first.