It’s true that the challenges of online assessment are all part of the HyFlex experience too. So whatever measures you use to reduce cheating in online assessments for fully online courses would likely be useful for HyFlex courses too. If you can’t have reliable and effective proctoring to reduce cheating on exams, then changing the design of the online quizzes and exams may be your best approach. (May be a good approach in any case.) There is a lot of guidance on redesigning assessments for reducing the likelihood of cheating. Some good basic guidance can be found here: https://www.facultyfocus.com/articles/educational-assessment/fourteen-simple-strategies-to-reduce-cheating-on-online-examinations/ And if traditional exams/quizzes are not required, you might consider other forms of assessment maybe more “authentic” to the discipline. See this resource for more on that: https://citl.indiana.edu/teaching-resources/assessing-student-learning/authentic-assessment/index.html