Uhm, I'm confused. "Lower Mizzenmast yard" to me is the "cro'jack" or "cross jack" yard, whose function is the spread the foot of the mizzen topsail. And to occasionally carry a mizzen course sail set flying, for those times when the spanker would be hemmed in by the rigging of the shrouds.
Royal sails were often set "flying"--to mean without permanent affixing to the mast. So, they'd have a rope parrel, and a halyard block set to a shoulder, rather than a sheave set through the mast. A flaying royal would have no lifts, and would come to the deck entire when unshipped. The royal was spread by the topgallant, which was generally a fixed yard hoisted into lifts with a batten and roller parrel.
The Skysail would be set flying above that. Contemporary accounts suggest that best practice was to set up the halyard to the opposite hand of the royal, to keep things ship-shape at the top.