Here is one image of both chalk drawings I did (with the support of Themisto97 and Lrond in case of Wachmann) on Friday 27th of July at the GalaCon 2018.  
My plan was to also add Sanni soda (much like in this picture) and I had completed the outlines and her mane and tail. After that however I had to interrupt to rush to a panel and later on to my own origami panel and workshop. During those panels there was first a moderate rainfall which left the images intact enough, but then there was a strong downpour which left just this of the above drawings:  
Canni Soda  
Wachmann  
After that I abandoned drawing Sanni Soda (I don’t have any image of her partly finished drawing).  
But on Sunday (same as in 2017) the chalk drawing really took off ;)