So, are you wanting additional decor for directly above the fireplace? The 6 pieces of art in the photo are staying and you want additional art, as I understand it? You could just take the top two frames and put them over the fireplace midway between the opposite 4.

I'd take the top 4 pieces over the TV and move them above the fireplace. Leave the lower 2 over the TV where they are.

If you add art over the fireplace you will have two competing spaces. I would suggest only having one. I would move the tv over the fireplace and add an additional row of art under the gallery you have already started. Because the art wall has more bulk, it will be where the eye focuses.

What you currently have is the tv and the fireplace fighting each other because there are two black boxes next to each other and the tv is also sitting on a black base. Because your art is all monochromatic, you could also add colorful art over the fireplace and that would draw the eye back to the fireplace. I am no expert. I made all of this up so take it for what it is.