how do I reconfigure extended wifi network with multiple base stations
I have a wifi network of an Airport Extreme hardwired to our ISP's modem, and an Airport Express extended wirelessly in another part of the house. I recently added a second Airport Extreme (also extended wirelessly) to boost coverage in another area of the house. I want to have the Express and the second Extreme each connect wirelessly directly to the base station at the modem to have the shortest path back to the main base station, but the Airport utility network schematic seems to keep showing the network in a linear fashion (Extreme main base - second Extreme - Express). So, two questions: first, is the Airport utility diagram representative of the actual signal path (linear from Express through Extreme II and then to Extreme II/modem)? And second, if so, how do I reconfigure the network to have both Express and Extreme II branch off the base Extreme I directly rather than having the Express feed through Extreme II and then on to Extreme I. The network showed as the desired branched network yesterday, but today dropped back into the linear path. I tried a simple graphical drag and drop to move the Express, thinking that surely Apple would implement such a simple, logical, and direct way to manage the network, but nope. Didn't see any other way to manually configure the network, so any suggestions would be appreciated.
iMac (24-inch Mid 2007), OS X El Capitan (10.11.6)