We use s with caron COMBINING CARON U+030C
but also s with curved breve (curving up) COMBINING BREVE U+0306
in a book we are typesetting with luatex using an adobe Berkeley opentype font on a mac
but it just outputs a plain s with no accent and no error.
It seems unicode suggests combining diacritical marks as the best way to add accents to a character.
What is the best way to implement this with this opentype font and luatex? Other suggestions are welcome.