Fallback doesn't import bouquets. You need to set up bouquets manually and the channels must exist on the server box.
To import bouquets from multiple locations you need to use RemoteChannelsStreamConvertor. This does not rely on fallback tuner at all and writes the stream URLs to the bouquets. But with time the bouquets go stale because they don't track the server box
Or ChannelsImporter plugin from OE-Alliance-Plugins, uses fallback. On boot it imports the bouquets, lamedb, and EPG from the server box. And it keep the channel list and EPG list fresh by reimporting every few hours (as selected in the plugin setup). Using this plugin the channels list is identical to the server box.