How to save a local backup project to a project already existing online

I've been saving a project I'm working on as a public project online, but if Musescore 4 has been open for too long it starts failing to save (I haven't saved the error like I should've, but it's something along the lines of authentication error or something close to that). So, when that happens I have to save the project locally to not lose the progress since the last save, but then when I save again it just saves to that local project. What I want to do is save the local file to that cloud saved project, but I have not yet figured out how to do that without it creating a duplicate file online. There's probably a simple solution, but I haven't found it yet, so I decided I might as well ask.

and I might as well mention while I'm here - the project online has been processing for 23 hours so far. I don't know what's causing to to take so long. I'm guessing it's stuck for some reason, but it could also just be processing very slowly. I have no way of knowing.

I attached the local file, just in case it's useful, but I'm guessing it isn't. No reason not to though. And here's the link to the online project (I think it's the right link): https://musescore.com/user/41970890/scores/14176984