I asked a similar question in the past, namely, I wanted to just use the Bodoni font for the greek letters.
Now I need to use ebgaramond font family, but my effort to follow the answer to my old question did not prove to be fruitful...
The suggested answer was to use substitutefont package, but changing bodoni to ebgaramond does not seem to work... Please help!
My old question: Using only greek fonts from a certain fonts package