suppose you could. I have mulled this over a while ago myself.
but I suspect you would have to go to the directories, and have to create the sub-directories first.
thing to watch out for, is whether the charts then picks up the .ex4 from correct sub-directory, eg, ../alpari/experts/indicators/oscillators/*.ex4.
alternatively, you could just rename them with a prefix, so they group together in the existing current directory.
eg, rename stochastics osc_stochastics, etc. that way all oscillators will list together. similarly with ma_ema, ma_sma, etc.