Hey @ssozonoff you can find the schematic here in the AssemblyDrawing.pdf file.
See below. The 3V3 supply on the AF powers both the Notecard and Feather, the the F_EN pin goes to the Feather EN and EN on this 3V3 supply. You can test this yourself by removing the Feather from the AF and pulling EN to ground, which will disable the Notecard.
There are a few other particulars to consider here with the AF and running on batter and in sleep mode, including needing a level-shifter on SCL/SDA to isolate the Notecard and Feather when the Feather is powered off. We’re considering improvements in a future spin of the board, but your best bet right now is to run off an AL if you’re looking to sleep a battery-powered host.