Some great responses so far!
From your post, it seems you walked right into damage control mode without realizing it. But that's where you are now -- trying to fix problems someone else left behind.
I had to do that in a scene shop maybe ten years ago, but at least I was forewarned and could plan my strategy. Basically, on my first day, I sat everyone down to a meeting (with lots of food) and said, guys, as of today, there's a new regime here and a different way of doing things -- we're going to run this place like a professional shop. Then I proceeded, while they were happily munching away, not to give them a bunch of rules, but to explain, nicely, where I was coming from and why. I also made it a point to say, I'm not your boss; you don't work for me. You -- we all -- work for the audiences that spend their time and money to come here and see a show. If we all want to keep our jobs, we have to keep the customers coming back.
A month or so later my boss told me she had noticed the crew seemed a lot happier and the camaraderie was far better than before. And all it took was explaining what I expected and softening the blow with some goodies. :-)
Is sounds like you're starting to do some of this, and yes it'll be a lot easier once some of these kids graduate and fresh ones come in. In the meantime, I might suggest a couple of things.
One, realize that most people out there do not understand theatre, but they're always happy to make assumptions about what it is and how it works. To that, you add that a lot of people do not like change. So keep explaining and educating them.
Two, I would consider talking to that other theatre company you mentioned. Maybe they have no clue what you're doing and that your shows are overlapping, but maybe there's a way around this. If nothing else, they can certainly support you by reinforcing that doing two shows at once helps neither one. And who knows, they could even become a resource for you in terms of borrowing stuff or people back and forth.
Third, I would talk to the "big" coaches at your school. They probably have rules and regulations and such about attending practice and so on, and may even have a couple of ways of handling prima donnas. And, if they have a policy of a kid not being in two sports at once, there's a precedent for you when you present your case.
Go for it, and keep us posted!
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George F. Ledo
Set designer
www.setdesignandtech.wordpress.comwww.georgefledo.net