Ideally, both riders should be proficient at Walk and Trot, possibly with Canter experience.
 
Whilst we can teach 2x Beginners together in a Semi Private Format, ideally we would need 2 Instructors, so each person gets the attention needed when you first start riding.Alternatively, a single instructor can teach 2 Total Beginners together but handlers would be required until Walk and Trot is established and the riders are experienced enough to control the horse themselves to a basic level.
This does require additional staff, and an additional fee might be required for Total Beginners, and subject to availability which is highly limited. So this isn't a guaranteed service, but can sometimes be arranged.