I have always insisted that parents of very young students join us for the lesson. If siblings, younger or older, are brought to the lesson appointment then they are not only welcome but encouraged to attend instead of sitting in the waiting area. It's probably the secret to my success with children. The process is shared between the family and the child.
I used to think that the kids would be inhibited by their parents presence. But after I changed my policy I realized just how wrong I was. The kids are actually a little calmer and a bit more focused with a parent involved. Younger siblings can be a bit disruptive, but not as much as you might think. And the student is used to it anyway. It's just like home.
Sometimes they invite their friends to join us. I don't mind as long as the friends are well behaved. Other times there are extended family members, grandparents, cousins, etc. Again, all are welcome. However the results have been comical at times when my modest, little teaching studio was packed like a clown car. But c'mon.....these are guitar lessons. They are supposed to be fun.
An unforeseen benefit is that the parents and/or siblings become students. After watching the lessons for a while they become intrigued and decide to take a turn. I had a seven year old begin lessons this week. His older brother had been a student about 3 years ago, albeit not a very good one. But little Josh would come in to watch and end up "hijacking" a portion of the lesson so that he could strum his ukulele for me. After his brother quit taking lessons I lost contact with the family until this week. The interesting thing is that when his mother was quite young her mother (Josh's Grandmother) took lessons from me.
In my current schedule I have three sets of siblings, two mother and son combinations, and one father and son combination. The really fun part is that this is not unusual. I can look back over my career and remember many families that had two or more members taking lessons from me. The students nearly always seem to benefit from this. And, while I'm not exactly a member of the family, I am a shared family experience. Like that odd uncle that you only see at special events, or the crazy cat person that lives down the street.
Learning generally takes place in a vacuum. Even when in a classroom, students are expected to be quiet, not talk to their neighbors, and do their own work. A form of social isolation. A solitary activity in a room full of peers. I'm not smart enough to debate the merits of this process, but I like the way that I teach better.
I take pleasure knowing that sometime in the future some of these families will begin a conversation with an uncontrolled chuckle and the sentence, "Do you remember that one time at guitar lessons when..?" And then later the guitars come out.