Hello, in my opinion Anna is the best model you had, yet. Please continue to make videos with her. 
Please make her record solo videos like Aigul! If she can't poop on the slaves maybe let her record her regular poops at home! Make her show her butt or feet, first. Poop for the camera, show the poop in close-up. Maybe talk to the slaves, like in the Aigul videos! I would buy them for sure! 
Or even make her poop on the toilet like in the very old Christina solo videos, then show her shit in the toilet...