Logic Pro X Play two MIDI instruments at once?

Long, long ago, when Logic was Notator, I remember you could create instrument groups that would all play at once when you provided MIDI input. I can't remember when that disappeared, but it occurred to me that maybe it didn't; many Logic features just got buried in arcane menu items and only the real pros knew how to find them. So I'm asking: is there a way to play my keyboard and trigger two different MIDI instruments at the same time in Logic X?
Are you talking about hardware instruments or software?

If its hardware, I think this will work: create two External Instrument. software instruments and assign their MIDI channels and audio inputs.
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Then select the two and create a Summing track stack.
With software instruments just load the two and create the Summing Stack.