On the datasheet it says the SYNC pin could be used to implement interleaved PFC with multiple ADP1047 or ADP1048 (at the PWM FREQUENCY SYNCHRONIZATION section).
To my comprehension, I would need to connect a source clock to both SYNC pin and manually adjust PWM settings in the GUI to make the phases of multiple ADP1047 or ADP1048 interleaved?
If you want to just interleave two PFC's use ADP1048 as this chip supports interleaving and current balancing. If you want to interleave more than this then the SYNC pin is useful and you can adjust the phase shift as shown in the GUI. I've attached a snapshot below from ADP1048.
Lt Comm Data.