The most recently used (MRU) source list remains resident on the user's system. The setup functions internally handle the creation of new source lists and their location on the user's machine. The setup functions use this list to store information about source paths used in previous installations.
You can use this information when prompting the user for a source path. For example, you could create a drop-down list of the network connections used as source paths in previous installations.
Depending on your permissions, you can create a user list, one that is specific to a particular user, or a system list, one that is the same for all users. In addition to system and user source lists you can create a temporary source list that is discarded when the setup application exits.