It sounds like Chad's future gigs are probably well-handled internally.
As a courtesy to clients who were perhaps specifically expecting Chad, I would allow them to cancel, though since you are technically able to fulfill the contracts I wouldn't necessarily offer any deposits back. (After all, considering the situation you could just keep their deposits AND not provide any services). On the other hand, this was Chad's responsibility and he's not here to fulfill it. That doesn't mean that you or his parents or anyone else have to. Very likely you could sell off his equipmet to more than cover the deposits he had received for events so you might want to think about that, too.
It's very noble of you to try and honor his committments. While it may be painful, it also may be somewhat therapeutic for you and some of Chad's other friend/roadies. It's hard to say. Just don't take on more than you can handle.
That said, we have a large company that covers OKC and Tulsa. If we can help with roadies, covering gigs or whatever let me know. I'm sure we can work something out. PM me here and I'll shoot you back our email address and phone number if you need it.
Good luck with this and God Bless.
Steve