Sadly I have to say "good luck with that" if you're using Django, as the forms library does not support partial form data out of the box, and it's architectural design makes this difficult to achieve. This is a particularly annoying restriction of Django, especially when building REST APIs. I'm pretty sure I did a thread about this a while back, but can't seem to find it.
I have written a set of mixins that add support for this, specifically for our use case of building REST APIs, so it's compatibility with other modules is minimal (e.g. there's no django admin support), but it would give you a good base to work from. I haven't done a proper lib release for this yet, but here's a dump for reference;
(this is super alpha, with no regression tests and zero guarantees of future or even current stability)
However - the above won't help you if you're using the traditional approach of binding together your frontend and backend (e.g. handling forms with traditional <form> post, rather than using JS), mostly because it doesn't make any attempt to modify form rendering, only form processing/validation. But if someone is serious about building an application with a proper UI and conflict resolution, they (probably) would be separating their API anyway, so this would become a non-issue.
And then of course we go even deeper into the rabbit hole, if you want to listen for event changes within the UI (e.g. warn about conflicts before submit is pushed) then using the "browser pull" method is not good enough (e.g. pull every X seconds to update your local storage). Instead you'd probably want to look into websockets with a pub/sub style approach, and this is something which is absolutely not supported by Django (and probably never will be).
But if we put the "big picture" to one side and look at this practically, unless you're planning on building a complete client side JS package, then you can pretty much ignore all of the above. Many people get along just fine with not separating frontend/backend, and it is arguably more work to do it properly - which is disappointing.
This is yet another topic I'm planning on doing a longer talk about in the next few months, along with a skeleton project to get people started quicker and hopefully change attitudes in the way forms are handled. It's all working internally, just need to spend some time making it good enough for public consumption :)
Cal