I’m brand new to Cubase (12), migrating from Pro Tools and very confused about how Cubase processes my midi tracks when composing. Regardless of which mode I’m using, Cubase only functions in merge mode. I cant replace parts at all, except by erasing them and starting over. The whole workflow around recording midi seems very cumbersome and bizarre to me. I’m a pianist and I’m used to working in linear fashion and very quickly. I want to play, go back two bars and punch in on the fly and keep playing. Cubase doesn’t want to do this at all. I can’t find any videos on midi recording that address this or anyone with a real keyboard-playing background and how they get around. I may need some tutoring but I need to find out if Cubase is really going to be functional for me.
Sorry if I misunderstand, but are you saying that even with selecting the appropiate options in the ‘setup midi record modes’ on the transport bar, it still always merges midi? As what you are trying to achieve should be easily possible. 
Correct. New Parts, Merge and Replace all act as Merge for me. Crazy, right? Also, I’m not using cycle record but did mess with those settings to see if it mattered, but it didn’t.
Sorry, i’m at a loss then, are you using the ‘Show lanes’ option on each midi track?
Of course could be a bug i’m unaware of, someone more knowledgeable than me will chime in soon enough I’m sure.
You’re very kind. I am not using lanes but I’ll give it a try. Thank you.
I only ask, as sometimes it may look like a part has merged, but in fact it’s on a different lane.
Yeah, this whole “lanes” thing drives me crazy, too. But whether or not that’s the case, both parts play simultaneously so the effect is Merge. Can’t I just punch and move forward without saving unwanted takes?
Sorry I’m unable to be more help.
Maybe tag this post with ‘Cubase 12’, May help it get more views.