Combis with sustain

[jakang]

So.. I´m new to this forum, but searching through the topics, it gets pretty obvious that i´m not alone with this problem!

My live rigg contains of just one M50. My question is..
In combi mode, can I play a piano patch and bring in a synth pad or strings on top?
I would like to be able to hold a chord with the sustain pedal, and with the next chord bring in strings on top of the clean piano without split or muting sounds, if its possible.

I´m about to play a David Paich (Toto) solo, in wich he starts with just a piano sound and now and then he brings in a pad/string sound over the piano, seamless. I think he does it with a pedal.

Is this kind of funktion more common on stagepianos than workstations like the M50?