Question regarding cross grading

I have actually two questions, the first is this: What does cross grading actually mean? I’m using a full version of Sibelius at the moment. If I cross grade does this mean that I can keep using and possibly upgrading Sibelius or does it mean that I can use Sibelius on the version that I already have but no upgrading, or does it mean that I’ll have to stop using Sibelius at some point?
Second question: I have a full version of Cubase and Wave Lab and of course I’m using the usb dongle that I got when I purchased the products. All my Sternberg licences are on the same dongle. Will I be able to put the Dorico licence on that dongle, and if I can does that mean that I could put Dorico on multiple computers and just move the dongle from one to another to use the program, exactly as I do with Cubase?
Thanks, I’ve been waiting a long time to get this program and I think it will be great to start using the first notation program of the 21st century.

A crossgrade is basically a special price for a user of a competitive product to entice you to add a new product to your toolset, in the hopes that you will prefer that new product to your older one, and become a customer of the new product in the future in preference to your old product. In the case of crossgrading to Dorico from Finale or Sibelius, you won’t have to give up your old product, and you will be able to both continue using and indeed purchasing further upgrades for them if you choose.

You will be able to put your Dorico license onto your existing USB-eLicenser and then run Dorico on your computers in exactly the same way you do with Cubase.

how about crossgrading from Cubase 5 to Dorico ?? is it possible ??