I have Magix Music Maker 2013 and I cannot adjust the tempos within a given project. This is needed for the midi channels more than vocal. but I need it so the vocal can have the necessary ritardando and accellerando.
I believe you're asking too much of MMM - it's not that sophisticated.
Obviously, with the quantization turned off, you can play any tempo you wish in MIDI. But, you can Timestretch individual audio objects so that their apparent tempo is different than the arrangement tempo.