Transforming a gallery wall into Christmas theme - wanted to share!

I found an easy way to transform my gallery wall into a Christmas theme. It took a long time to get the spacing right when I first put up my gallery wall. I did not want to take down all the pictures, hang up the Christmas ones, then have to figure out how / where to place my old pictures back up. I also did not want to put multiple holes in my wall. I used the existing frames and just slapped the new picture up with sticky tack on top of the old pictures. I painted my Christmas pictures on thin plywood so they are not heavy, yet sturdy. (If you do this, you will want to be sure to paint the sides of the wood.