When you save a section of your map as a linked map you add the linked map as an attachment to the source map. When you do that you are given the option of where to save the linked map. If you choose a network or other accessible location for the linked map your colleagues could open it/them, make their edits and save.
Each time you open the linked map MindGenius will pull it from the network location and you will see the edits made by your colleagues. Should you attempt to do this while one of them is editing the map you will be informed that the map is locked for editing and by whom.