Chosen Solution
just installed second 250gb SSD on my iMac to install windows here. tried different ways and programs from internet but nothing helps . BootCamp can’t recognize second SSD, only shows main SSD.
BootCamp will only work off a single drive/partition where both macOS and Windows OS’s sit. You can use a second drive (or multiples) as data drives for either OS (or even other OS’s). Your only means to run dual OS is full isolation (requiring a reboot to switch) without using a VM product. A Virtual Machine (VM) can do what you want but its much harder to setup with multiple drives and some products are not able to do it.
