One potential advantage of a system like Carrelet over a traditional FTP-based system is that it is very easy to let different people take responsibility for different parts of the site, whilst maintaining some measure of consistency.
It is important to note at this point that there is a fundamental difference between the logical structure of the site, as expressed through a series of parent-child relationships, and the implementational structure on the hard disc of the server. All Carrelet accounts are stored at the same level, and, in terms of their respective urls, one account is never 'under' or 'in' another. However, it is possible to link accounts so that the navigation occurs as if the accounts were indeed arranged in a hierarchy.
This involves two steps:
Both the parent and child sites will need to be 'remade' by going to the global settings page and clicking on 'modify' for the changes to take effect.
On a technical level, it is trivially simple to give different access codes to different people for different Carrelet accounts. If you are planning to use multiple accounts, it is worth thinking about the password strategy before the accounts are set up. If one person is going to be responsible for the whole site, you might as well use the same password for all his accounts. If, on the other hand, you want to delegate responsibility, ask for a different password for each person (who may have one or more accounts).