Is it possible to set anything, like a relative path/folder for the parts in an assembly? I am asking, because I and my supervisor work through a shared dropbox folder, and when I publish there my assembly and parts, my supervisor cannot open it.
There are 2 things that could be wrong. One being that you may be trying to open parts at the same time, and when one person has the file open, the other cannot regardless of any case unless it is opened as a read-only. The second case is that the files may be set with permissions that do not allow your supervisor to open the files. This is typically changed in the file properties that you check in the drop-box. You would right click the file, go to properties, and there should be a tab where that can be changed. I can't really think of anything else it could be.
Yes the paths should be the same. Such as there is a shared folder for everyone to access. All files that are trying to be shared should be kept on a network style drive available to everyone. Otherwise, everyone will end up with different versions or not have access to the most up to date files.