It is possible to let another user register expenses for you. An example might be an assistant registering expenses for the assistance's superior.
Go to the User view in backend and find the user who is going to help someone else to register its expenses. Click Allow user to register expenses for others and search for the user who is going to get help with registering its expenses.
As an example, if Dave is going to help Lisa register her expenses you go to Dave in the user view and search for Lisa.