Dual boot on new ssd

Hello everyone!

I’m here for some advice about dual booting on my machine. I’m currently working with 2 separate HDD: one with Windows on and the other one with Manjaro. I found this configuration really easy to maintain during the years and I’d like to keep it like this now that I’m moving one of the HDD to a SSD. My plan is to reinstall Manjaro on the SSD (I’m using it to work so It would be the best solution) and to keep Windows on the other HDD for games and family stuff (it will stay slower but I don’t really care).

There is a catch, tough: everything is running in old BIOS legacy mode, and I’d like to update everything to UEFI now that I have the opportunity.

So, given this, my plan was something like this:

1. Install Manjaro on the new SSD;

2. Use something like mkusb to flash a usb with W10 on it;

3. Install W10 on the other HDD without touching the SSD (I hope there will be some options to totally exclude the SSD drive from the installation of Windows);

4. Set the SSD as first boot device, where GRUB loader will be found;

5. Update the GRUB so it catches W10 on the other HDD too.

Now, I have a little experience with dual boot installation but definitely not enough to see potential problems coming out from this plan. Am I planning it correctly? Any advice to make this work properly?

At the moment, since I’m booting from the MBR of the Manjaro drive, the GRUB just catches the Windows boot-loader on the other drive and lists it as a choice. But after going UEFI what should I expect?

I also heard that installing Windows after a Linux distro may be more problematic than the other way around. Should I install Windows as first? Placing only the EFI of Windows on the new SSD and then installing Manjaro alongside?

Sorry for the lenght and the confusion and thanks a lot for any advice you can give!