Conversation so far:
Why did Serebro change their record label
In January 2013, Serebro announced that they would release their further material in Japan after signing with EMI Music.
Why did Serebro choose Japan to release their further material in after signing with EMI Music
This was after the decline of Serebro's success after Mama Lover
What projects were Serebro working on after the decline of their success after Mama Lover
Serebro announced that they plan to release a compilation entitled Serebration that includes songs from their first and second studio albums.

Question: Did they work on anything else?
Self-contained rewrite: Did Serebro work on anything else besides a compilation entitled Serebration that includes songs from their first and second studio albums?