Is there a way to play TimeSynth clip by "fade-in" from the specified number of bars?'

Question about TimeSynth.

Is there a way to play TimeSynth clip by “fade-in” from the specified number of bars?

(What I want to do is: )
while “MusicA” is playing on 10th bar,
to stop by “fade-out” MusicA, and
play “MusicB” by “fade-in” from 10th bar.