Pitch Bend (PB) Change is not Control Change (CC), that is different MIDI message type. In Piano Roll PB is called "Wheel" (CC is called "Control"). The "granularity" of PB is a MIDI Channel. PB is specified by current absolute value, which is valid for everything on the Channel till the new value is specified.
So, there is no way to say "Bend up a bit from previous bend down". Every event will set new value, independent from previous conditions.
But it is still possible to specify up to 16 different PB, so different for each channel, in one MIDI clip. In case notes are coming on different channels and Synth is able to work with that (for example, TTS-1), that can have desired effect.
I have just tested the following: TTS-1, Channel 1 and Channel 2 are "Piano 1". One note on channel 1, another on channel 2, with 2 "Wheel" envelopes in different directions. So, one note is bended up and another down, simultaneously!