The datasheet describes paralleling 4 of these devices in section 7.3.7.3. Does the below diagram still hold true for connecting 3 devices in parallel, excluding device #4?
Below is the way I've connected the three devices in parallel using the SYNC pins. External resistors for RT are utilized for device #2 and #3, while device #1 is left open.
1. SYNC1_primary to SYNC1_device3
2. SYNC2_primary to SYNC1_device2
3. SYNC2_device2 to VIN
4. SYNC2_device3 to GND