It happens more often than one would expect.
You find yourself dealing not only with an employee, but their parents. It can come up in a couple of different ways:
A parent wanting to participate in the job interview
A parent calling in sick for their kid
A parent showing up for a performance related meeting
No matter what direction it takes, it certainly puts HR or a small business owner in an uncomfortable spot. When situations like this come up, the question always is, "Do you have to let the employee have their parent present?"
The short answer is NO, as long as your employee is of legal age.
Employers set the tone for the workplace and if you're employee brings their parent to a performance meeting or has them call in sick for them, it's up to you as the employer to say something. Saying nothing at all and not addressing it sends the message that that type of behavior is acceptable for the workplace.
Take a look at your policies. Do you have a policy about who can be present at performance related meetings. In a union environment, there are certain rights employees have called Weingarten Rights however in a non-union environment, employers can set standards as to who can be present.
Do you have a set call-out procedure that details what's an acceptable way for an employee to call out for their shift? If yes, then address it with the employee for not following the appropriate procedure. If you don't have a set call-out procedure, GET ONE.
I'll preach this all day long, as an employer, even if you have one employee, you need set policies and procedures in order to mitigate your risk.