Hi psievert,
If you want multiple people to be able to upload to the same AxShare ID, then what you’ll want to do is make use of the Workspaces feature on AxShare. To do that, log in to your AxShare account and create a new folder. Place the project within that folder, and then share it with the people who will also be working on it. They will receive the email invitations via email (be sure you send it to the email that they used for their AxShare accounts), which will allow them to download, edit, and upload the file to the same AxShare ID. Here’s a bit about the Workspaces feature:
Axure Forums - Introducing Workspaces – A New Way to Organize Your Projects
The downside to Workspaces is that if multiple people intend to work on the same project at the same time, then only the file that was last uploaded will be visible to your stakeholders. For example, if user A makes changes to page 1 and uploads the file, but then user B makes changes to page 2 and uploads after user A, the AxShare link will only show the file uploaded by user B. No changes to page 1 will be recorded.
The best way for your team members to work simultaneously on different parts of the project while avoiding overwriting anybody else’s work is to use the Team Projects feature. If you take the most up to date RP file and create a Team Project from it, then everyone should be able to begin working together on that project. If you need the stakeholders to see the most up to date version of that file, you can export the Team Project to an RP file and upload the file to AxShare.
Hopefully that helps!