Latching Arpeggiator

Does someone know how to make a latching arpeggiator with Cubase 11 or Groove Agent 5? One that lets you add notes to a pattern of, say, 2 bars? I think this is what Tangerine Dream used to make their amazing loops.

Play a note in beat 1
1x 2 3 4 5 6 7 8
it latches
1x 2 3 4 5 6 7 8
add a note after beat 3
1x 2 3x 4 5 6 7 8
it latches
1x 2 3x 4 5 6 7 8
1x 2 3x 4 5 6 7 8

An old synth I once used had this feature built in PLUS you could play a note that was already in the pattern to erase just that note!

Anyone know how to do something similar? Is it possible to live record MIDI and have the recorded notes play back while recording more notes?

Yes. Look at the different MIDI Record Modes.