XPS 8700, What causes the C drive (Drive0) to become (Drive 1) when adding HDD?

Here are two articles that may help, but it appears that this is something that is difficult to change.

https://support.microsoft.com/en-us/help/937251/disk-drive-numbers-may-not-correspond-to-the-sata-channel-numbers-when

https://www.dell.com/community/Desktops-General/D-Drive-is-drive-0-C-drive-is-drive-1-How-to-change/td-p/5174704

we can't see your pics.

Drive-0 and Drive-1 usually correlate to SATA-channels and are normally irrelevant.

Thank you Tesla1856,

I repost the picture here, but it shows on my PC, let me know if it still does not show.  I know it does not show if not logged in.  Maybe some limitations of size or similar?

Thank you Vic384,

That's very helpful in getting my head around what is going on and the way Windows assigns the Drive number.
I take it from the fact this has already come up that there is no real way to force a Drive & letter combo.

I guess I am still surprised that my (as yet unformatted) secondary drive gets allocated first, because the main drive is an mSATA - but it is shown listed last in the Dell BIOS... maybe that's why, but I can't see a way to change that order.

 Just so I don't make a silly mistake would you recommend which port numbers I plug the secondary drive in, and also the DVD ? [ 'cos the mSata is 0 anyway I guess] .  I got the impression that there may be certain combinations that  may cause issues.

Finally, should I format the secondary only when the drives are correct, or can I format straight away ?