So, John is responsible for old documents, and he needs to add more items into it. Instead of asking you to add those items, you can give him access to the project, and let him do it himself.
Let’s say that John has already signed up in P3pper, and his username is john. To give him access to the project, open the project page and go to the stakeholders section. There’s a box with the label add a new stakeholder; type john and press the Enter key or click on the Add button.
Now you can see john in the list of direct stakeholders for the project, with access level of L1. Click on the edit link in front of john to see the access levels and select one. You probably want to give him L6, to be able to add new items to the deliverables map.