Note off Chord

Hello,

I'm new in max. I would like to gather note-ons and note-offs messages, in the aim to send a global OSC message "onKeyPressed" and "onKeyReleased".
When I'm playing on a midi keyboard, I detect each note-ons and each note-offs. I would like to gather them, specially when I'm playing chords.
For note-ons, I use quickthresh, that's not so bad. Even if when I play with the right hand, I send one "onKeyPressed", I should not send another message if I add my left hand. The ideal would be to send a onKeyPressed only if I had previously a note-offs global message.
And the big issue I got too is how to do this with note-offs properly.

Any suggestion on which method I may use would be a good help.
Thanks

Olgarym