Over the years our 1898 home has settled, creating two 1/2" gaps between the tiles in our fireplace surround. The previous owner filled the space with portland cement that has since fallen apart (and it looked pretty awful too!). We've since removed the gaps and just shoved in some plastic tile spacers, just so the tile doesn't fall in the interim. We'd like "align" the gaps and fill the space with small accent tiles. What's the best way to move 3 rows of tile down so the gaps are on the same horizontal line? And what's the appropriate way to fill the space behind the tile and affix new accent tiles in the gaps?