Surely she cleans out her closets and sells or donates. Find out where or to whom LOL. (Don’t imagine she wears anything more than once or twice)
OTOH, there are several very UPSCALE secondhand clothing stores in NYC ( Manhattan ) were she might sell or donate ( private schools usually have a resale shop, to which parents are encouraged to donate stuff to ) but I'm not sure that the ones I knew of are still there.
:-) Good idea except she is 5'11" and I'm 5"2". LOL!