Well, I usually say
Dionysus as dye-o-NYE-sus, but I guess it's supposed to be dee-o-nuy-sos.
So I'd usually say dye-o-NYE-si-a but... dee-o-NUY-si-a? (I'm not entirely sure how to pronounce "nuy")
Usually when I read
Dionysia in my head it's dye-o-NYE-si-a or dye-o-NIS-i-a.
DiDio
Dyo
Dia
Dya
DeeNyssaNyssie
Nys
Nysi
Nysia
Sia
NyxNyxie
Dixie (I don't like that one though)
IoIon ??
Si
Sisi (don't like that either)