Well, MusicXML support would be useful.
It should be not much a problem to program that code.

Also there should be implemented the whole MusicXML DTD as possible additions to the notation window. You should be able to put notes and every other type of signs in a score editor, like it is in Musescore.
Musescore is in GNU General Public License. So you could even use the source code from it to implement it into BIAB.

Regarding Sinsy: Maybe there should be a possibility to involve the Vocaloid software as well, because those vocals sound much better that Sinsy.

Michael Frank