Thai font fallback for Unity Android

We are having an issue supporting Thai characters in our game. Unity allows falling back to the system font for CJK however not for Thai. Does anyone know of a way to specify an additional fallback font? Other alternatives such as sysfont and ngui substantially increase the file size so we would like to avoid this.

 

In my thai language problem, there are not garbled but just empty in my android device. But English , Chinese, Japanese are all fine.
I just follow this method but it is not working.

 

You may have found the answer by now, but in case not, this might help.

I was having trouble getting fallback fonts to work, and it turned out I was not specifying the list of fonts correctly.
I had been formatting the list like this

Font1
Font2
Font3

Instead, it should be :

Font1,Font2,Font3

The documentation doesn't make this clear.