I'm playing on the outside of my desk, and my scroll is constantly in my stand partner's face. To have my violin off to the side seems kind of necessary for me to keep good posture, but this clearly isn't working. How can I modify my posture to keep my scroll more forward than to the side? Or whatever else needs to happen to address this problem.
If so, I have two suggestions. (Caveat: I'm a cellist, not a violinist. But I have been Suzuki coach for my two violist children.) Swivel your body a bit to the right, and think in terms of pointing your scroll at the stand. I'm having trouble finding a picture to illustrate this idea. Here's the best I've come up with.
The woman in the green skirt has her knees pointed slightly to her right. I actually think you could point your torso and knees a bit more to the right than that. More like the woman farther back, with short white hair. When you're practicing at home, you could work on getting used to pointing your scroll towards the music stand. If you're reasonably tall, you may want to put your stand on top of a few stacked encyclopedia books so you can still see the music well.
Second suggestion: Cellists need more elbow room than violinists when sitting in orchestra. So, from years of experience in getting the elbow room I need, to play comfortably in orchestra, here are my thoughts. You can do some negotiating with stand partner and other neighbors, but personally I also check and adjust the chair set-up when I come into the hall or the rehearsal room, before unpacking my instrument, greeting people, checking bowings, etc. I find it easier that way.
Because of the wedge shape of your section, you can often get a bit more space by moving your chair, your stand mate's chair, and the chairs behind you, back half a foot or a foot.
If you think about it -- is there any particular reason why violinists have to be packed like sardines? If your ensemble is too big for your stage, then yes, but most of the time, I don't think so!
The answer should be pretty obvious: take a look at all the other violinists. How are their torsos oriented, and at what angle to their chests are they holding their violins? If you are holding yours at an extreme angle compared with the rest of them, then you probably should be evaluated by your teacher or other advanced violinist. And if it really turns out for musculo-skeletal reasons that you have to hold it that wide (which is unlikely!), you'll have to consider rotating your body away from your stand partner.
Now, with that said, why not just swap inner/outer chairs? Seems like a no-brainer from here.