I like to promote learning music with the whole family, so if multiple family members would like to learn together, I will tie their lessons together so they can learn alongside each other, and make music together.  God designed music as something to be shared and to bring people together.  I believe that a family learning music together is the perfect example of that.  Having the family involved in the learning process also helps with motivation and understanding of techniques.  If your family would like to have lessons together, sign up for each student individually, and then mention it with your lesson time.