This is where computer imaging isn’t exactly a smooth process. Unfortunately, machines implement displaying a drive however they see fit, even across the same model of different machines. Typically the channels that an HDD is connected to (SATA 0, SATA 1, etc…) are followed to some level, but sometimes this isn’t the case (as I imagine you’re seeing now).

It is possible to tell FOG which drive to use, though it doesn’t know if the drive is ssd or hybrid or spinner. This is completely dependent on the machine, and if you can’t rely on which will be populated as what letter (my guess is your machines were setup in RAID mode of sorts?) that isn’t really going to help you much.

One way you could do this though, is to swap out the /usr/share/fog/lib/ file and change the getHardDisk function to detect your drive sizes. (You can do the swap out using postinit scripts.) But then it’s implicit that all machines will follow the same method.

The steps I would take, albeit more time consuming initially:

Install the SSD to the 1st SATA Channel (if that’s how your machines are setup – I can’t help much in the case of NVMe/MMC builtin controllers as I have nothing to base them on yet).

Move the 1TB to the second SATA Channel.

Ensure the machine’s firmware is updated to the latest and greatest.

Ensure the machine’s SATA operation mode is AHCI.

If these don’t make your SSD display as /dev/sda then I don’t know else to tell you to try.