Apple juice has no protein in it, so no foam.
If you want to fortify a cider, ferment it for a week, then add the sugar. Too much osmotic pressure from the sugar makes yeast growth very slow.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk