Garmaine Staff asked 2 years ago

I recently bought a house ( about 15 years old) but just noticed that the back of the fireplace is cracked, it's about 1cm wide in the worst place. Can I repair this with fire clay/ cement? enter image description here

If i have to replace the firestone, do I have to take to whole fireplace out to repair?

Update, wider picture of fireplace enter image description here