Not really a Motif XF question, is it?

I highly recommend that use the Cubase Operation Manual and contact Steinberg for the best ways to proceed. I’m not saying that to duck answering the question, but there maybe some new tricks/features that can assist you in doing this. Steinberg has many features that can help you... depending on your version. Try the forum over at Steinberg.net(when you ask your question the version of Cubase will make a difference as to which features are available).

I can, generally, give you what you will want to do. I can give the concepts you will want to work out.

If you are doing a Genesis Medley, think it through as a virtual replication of the band... try to, for example, use the same drum kit throughout. Why?
1) Phil Collins probably didn’t change Kits in the middle of the gig and 2) changing drum kits with a program change is never a pretty thing.

Look for instrument programs that you can use throughout the entire medley, the less instrument changes you need to make the more undetectable it will be moving from one composition to another. Ultimately, all songs in your medley will be contained in the single Projectfile.

You want to learn to use the TEMPO TRACK so that adjustments to tempo can be made where necessary.

If you need to switch instruments, you might want to consider using a different track, if you have it available. For example, if for the first transition you need to have a different bass program, instead of having the instruments switch on a single track (via a Program Change), use another track so that you don’t have any issue (it always makes me laugh when someone wonders why they can hear a glitch or an interruption at the program change... its nothing that wouldn’t happen if you asked a human playing bass to switch from a MusicMan bass to a Fender bass in a 64th notes time, ha... to avoid that if you have enough tracks, use them... you might use Tracks 1-8 for Song 1, Tracks 9-16 for the second Song in the medley... this way there is room to breathe at the transitions.

That’s just an example... your track numbers may vary... you might just want to use the same drums, bass and guitar sounds throughout... this usually creates the illusion that it one band... and not a DJ who typical doesn’t care what the instrumentation of the musical ensemble is... if you are going for the illusion on a band, it helps to keep the instrumentation and the general mix settings similar.

Hope that helps get you started.