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Most BLDC motors utilize regenerated electricity. For example, an electric car uses this feature for braking and conserving battery capacity . This is a normal function of the BLDC motor.
I do not want this feature. I require the motor to coast as the default condition. If any of the 3 power supplies fail, then relays R2, R3,& R4 carrying the power to the motor will return to the "normally closed" position. All coils are then open circuit, and the motor should coast, or freewheel. The diode D2 at each High Side MOSFET allows current to return to the battery if the MOSFET fuse blows. This bypasses the intrinsic diode. D1  helps to prevent overheating of the HS MOSFET.
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A Detailed Look At Relays 5 & 6 Area
Q1 Are the MOSFETs

Relays are shown in power off position.
R1 will allow controlled regenerated current to go to batteries, in either position. If the 36volt fuse  blows then the relay must  close. Relay R1 coil operates directly from the aux 12v through the Main Switch.

Relay R5  is Jaycar SY4053  DPDT 24v coil or Altronics S4142B SPDT 

Relay R6  is Jaycar SY4052  DPDT 12v coil or Altronics S4140B 

The Jaycar relays will fit cradle SY4063,  but all are PCB mountable.