Thank you, for Remix and Sd card help. 
I had tried Remix OS as vdi, I will try as vhd tomorrow and write how it goes
It sounds a good what you are working on with the multi os and sd cards.
The Noobs pack it has multiple os on it, and you choose which one to download, on reboot you can access that menu again and change the installed os, I haven't tried that yet.
If you view the source code of how they do this you may be able to do it for your end goal and save card numbers, 3 or 4 cards less equals the price of a Pi3.... but then you'll want more sd cards ;D .
I use ones called Class 10 micro sd, 8GB, I have 3 so far, 1 PNY, and 2 Sandisk Ultra.
Update - have tried Remix OS as vhd, same errors, also tried resident, guest, and ide from boot menu.
Update 2 - I am unsure why but the Pixel VM resets on each boot, eg; I installed ufw and enabled it using the terminal, and installed Firefox using the software installer, I also changed the password, all were reset to default, or no longer installed.The next time it was booted.
I have had a practice now with the micro sd cards, I looked into how to do this and it said to use gparted, which comes installed in LL, although I hadn't used it before.
I have tried mounting a previously made card, as you wrote it mounts similar to a usb stick would.
I have also formated 2 cards using gparted in LL, successfully now.
Probably tomorrow I will add a build to a card using LL.
These may seem small things but they were things I had to do on windows until now, now I can do them on LL instead, it makes me
I also tested the first of my new micro sd card reader/writers that arrived today to do the above, which I hadn't had before, only multi card adapter so micro sd went into sd card adapter, then into adapter stick.
It's a nice small one and the micro sd fits directly into the end of the usb connection (very good fit), it then all goes inside the usb connection on the computer, it makes it smaller.
I had tried Remix OS as vdi, I will try as vhd tomorrow and write how it goes
It sounds a good what you are working on with the multi os and sd cards.
The Noobs pack it has multiple os on it, and you choose which one to download, on reboot you can access that menu again and change the installed os, I haven't tried that yet.
If you view the source code of how they do this you may be able to do it for your end goal and save card numbers, 3 or 4 cards less equals the price of a Pi3.... but then you'll want more sd cards ;D .
I use ones called Class 10 micro sd, 8GB, I have 3 so far, 1 PNY, and 2 Sandisk Ultra.
Update - have tried Remix OS as vhd, same errors, also tried resident, guest, and ide from boot menu.
Update 2 - I am unsure why but the Pixel VM resets on each boot, eg; I installed ufw and enabled it using the terminal, and installed Firefox using the software installer, I also changed the password, all were reset to default, or no longer installed.The next time it was booted.
I have had a practice now with the micro sd cards, I looked into how to do this and it said to use gparted, which comes installed in LL, although I hadn't used it before.
I have tried mounting a previously made card, as you wrote it mounts similar to a usb stick would.
I have also formated 2 cards using gparted in LL, successfully now.
Probably tomorrow I will add a build to a card using LL.
These may seem small things but they were things I had to do on windows until now, now I can do them on LL instead, it makes me
I also tested the first of my new micro sd card reader/writers that arrived today to do the above, which I hadn't had before, only multi card adapter so micro sd went into sd card adapter, then into adapter stick.
It's a nice small one and the micro sd fits directly into the end of the usb connection (very good fit), it then all goes inside the usb connection on the computer, it makes it smaller.