Let me give you some advice on this.
If you are flaky and unreliable when you have a small role in the chorus, your director will pr0bably not trust you with a lead. If you goof off and miss rehearsal frequently (unless you are excused) then the director will probably not seriously consider you for a larger role.
Parents: if you grumble about casting choices (don't kid yourself--this stuff always gets back to the director) and if you are half-hearted in filling your obligation to sell tickets or help with props or paint the set or whatever, then you are shooting your child's future chances in the foot.
If you are glib about your child missing rehearsals because of your lack of organization or planning, if you don't live up to the commitment that came with your child being part of the play, then you are sending the director a powerful message that you cannot be trusted.
Sadly, that means your child can't be trusted since your child is dependent on you for rides and logistical support.
If I can't trust you with little things, I will not trust you with big things. Far too many people work too hard on a play to take a chance on someone I can't fully trust.
You don't get the lead and then develop responsibility. You act responsibly with small things, earn trust, and then (assuming you also have talent) you get the lead. So many people want to do this in reverse. But life doesn't work like that.
I would add that while I'm talking about the context of theatre, this applies to many other things in life--sports teams, jobs, and so on. If you can't be trusted with little things no one will give you greater responsibilities.
This seems so obvious, and yet I am always astonished at the number of people who don't understand--and act--on this principle. I get that adolescents might not realize how this works, but I am surprised more parents don't get it.
Every year I'm shocked by the people who are shocked that they (or their children) didn't get big roles. Sometimes they haven't prepared adequately or worked to refine and stretch and develop their talents to the point that they could be seriously considered. Other times, perhaps most often, someone is talented but has goofed off a lot. Or a parent has been scattered, unsupportive, and not very good at making sure their child was where they needed to be.
Believe me, future stars, this makes a big, big difference. Trust me on this. I begin looking at potential lead material years and years in advance, watching carefully to see who has talent, but who has a good work ethic, who can focus. Who cares enough to try. And which parents will support them. I know other directors are the same in this regard, and I that that coaches are, too.
So, there it is! Free advice that will change your life. You are welcome.