This is a simple Python3 script which syncs emblems between Nautilus and Thunar. For each directory given it will go through the files and for each file merge the set of Nautilus emblems and Thunar emblems on it. Then if necessary update both the Nautilus and Thunar emblems to this new set.
This is a simple Nautilus extension which adds a context menu to files and directories which lets you set/modify emblems its emblems.