Creating new reference:
To achieve this you need to go to the shop-locator.js file. There you will find displayMarkers function. You will need to add there an extra reference for the .json file
Just like you can see on this image below:
Now you can add different marker for each place you want to show on your map.
Just go to the .json file where you are keeping all the json marker and add new field with the path to the image you want to use:
Please remember: All of the locations in the .json file need to have icon field with the path to the image.