Acoustic violin with DJ?

Professionals rehearse. I would raise your and your daughter's concerns with thr bride and the dj. At a minimum i would require a rehearsal with the dj at the venue.

Winging it is not a good idea.

Does the dj have experience working with acoustic instruments? Does thr dj exoect the violin to be miced?

Having a DJ and a live musician is not an uncommon setup—a musician for the more formal moments and someone who can play dance music on a sound system and take requests at the reception. Since DJ and musician are often lumped together under the heading of wedding music, so it’s not uncommon for people to think of them as interchangeable. Like anything, there is a risk of things not coming off well when uncertainty is introduced and when people who do different things are asked to collaborate. If the plan is clear and there’s enough lead time and good communication beforehand, it’s possible to make it work. If you’re winging it, it will come down to how quickly you can think on your feet, how open you are to making concessions, and the ability of the other party to collaborate.

One practical consideration is the sound. If the OP’s daughter is not being amplified, she’ll likely need to at least have a microphone available to her if she’s playing with a DJ unless the DJ is thoughtful enough to balance the sound levels with an acoustic violin and the venue has good enough acoustics for it to come off well. A good friend of mine plays weddings and brings his own complete sound system to all gigs. He has invested heavily in making his own custom pedal board and mixing setup so that, even if he ends up working with a DJ, he can manage the mixing himself so that someone else doesn’t do it poorly.

I don’t think the OP gave enough information about the bride to pass a judgment against her as a bridezilla and I don’t think price gouging in response to being asked to work with someone else is a very professional approach. An honest conversation about what’s realistic and how to achieve the desired outcome for all parties is much more appropriate in my mind.

My stress went way down with this decision. This is unlike any wedding she has ever played at before. Very disorganized.

I’ve been playing for weddings for 40 years and I would absolutely not agree to any part of this hot mess.

By the way about the thumb coming up on the left side of the neck. That's not what's pictured in Suzuki Book 1, but plenty of really good violinists play or played this way. Ray Chen, Ivry Gitlis, and Fritz Kreisler come to mind. I can't defend it or justify it, but I suspect that it depends on the "school" in which one was taught, and the size and shape of one's hands. I suspect a lot of violinists on the verge of true mastery are in a situation where they realize that they have to challenge these kinds of rules in order to break through. Chen studied with Aaron Rosand and in the linked video you can see Rosand's thumb coming up and down depending on the string and the stop. I think there are a lot of things one is taught as a child that just don't necessarily work at the highest level. The flip side is that mimicking the hand positions of Gitlis or Rosand might be a really bad way to start out on the violin. I've never taught violin so I can't really be sure.

I will say that in the long run this has been a good experience for dd to have had. Dd has an absolutely beautiful voice (her voice is far more advanced than her violin playing. She has been cast as lead female vocalist in multiple musical productions. Violin is her first love, though.) I think this entire dj/violin fiasco has spurred new perspectives. I think she needs to really start thinking outside of the teaching/violin gigging/chamber music future box. Ideas of learning how to incorporate all of her musical talents into a marketable niche might be a way to turn her musical loves into an actual way to earn a living.