Not sure how you have everything connected now, but all three synths have USB MIDI connections.
If you plug each of them in to your computer via USB, they should each be addressable as individual synths under Logic.
If you're daisy-chaining using the MIDI DIN connections, then by default the master synth (SubPhatty?) is going to send MIDI control signals on the same channels as the other synths, and each synth in the chain should respond. (I believe all the current Moog synths default to MIDI channel 1). You can set a different MIDI channel for each synth (see the respective owner's manual), and you'll also need to take a look at the default MIDI routing that is enabled for the synth that is connected via USB ~ there might be different options available that specify how MIDI data via the USB port is routed internally to the DIN ports. (again, reference the owner's manual for that particular synth)
MG-1, Little Phatty Solar CV, Minitaur, Slim Phatty (x2), MF-101, MF-102, MF-103, MF-104M, MF-105M, MF-108M, CP-251, Animoog, Filtatron, ..and some Doepfer stuff...