Creating a Boot Camp drive

Hi,

I'm using a mid-2011 27" iMac with Sierra 10.12.6 in a Fusion Drive (I added an SSD to the spare slot on the logic board). It has the latest firmware 87.0.0.0.0.

I want to create a Windows Boot Camp partition but because I have Fusion Drive, the Boot Camp Assistant won't work properly; I'll have to do it manually it seems.

I ran the Terminal command 'diskutil list' and this is the result:

I boot from the Logical Volume named 'Macintosh' as confirmed here:

On the HDD /dev/disk1 we can see that there is a partition named 'Sierra' along with an associated Recovery HD, identifiers disk1s4 and disk1s5 respectively. These are never used and AFAIK I could remove them and create the Boot Camp partition in that space, using Terminal commands.

Please could you expertly advise if this will work and it would be super-helpful if you could please inform the correct command procedure for this operation, ie. from eliminating the existing 2 partitions up to creating the bootable NTFS partition, into which I'll then install Windows 7 from a USB stick.

Thank you so much for your attention.

Andy