When you upload your game you can press the "More" button and click "Admins" then at the bottom you can add people and set them as contributors. That will allow them to edit the game's page and will add them to the jam entry.
When you upload your game you can press the "More" button and click "Admins" then at the bottom you can add people and set them as contributors. That will allow them to edit the game's page and will add them to the jam entry.