GIVE A LEG UP - TRATO DE FAVOR

"Give a leg up" Google translates into Spanish as "dar una pierna arriba" which is a good word-for-word translation but off the mark. WordReference gives us "levantar, aupar, dar ventaja" which come closer but still off the mark again, considering that the definition is: "To give someone an advantage over others" which brings to mind the Spanish equivalent of "dar trato de favor, trato discriminatorio a favor de alguien." 

Collins, always on cloud nine, says it is "a preferential treatment." 

— “Quieren saber si la Junta de Castilla y León dio trato de favor a la Caja Rural de Zamora.” El Mundo, 24/08/1994. Esp.

— “Wesleyan University… is ending legacy admissions, which give a leg up to the children of alumni.” New York Times, July 19, 2023. US.

Why point this out? Just to make students of either language aware of how dictionaries treat phraseology. In my dictionary I am attempting to remedy this problem.