When there are two or more VMMS available, one VMM must have a discrete input to wake up and then the rest of the VMM can be controlled with Wake on CAN and the Power control flag. In this example, Input 1 is from VMM 1 and the Power Control Flag is from VMM 2. When Input 1 goes active on VMM 1 a short time later, VMM 2 will wake up and process.
You can wake up all the VMMs without an input, however this will mean something else and the CAN Bus will have to send out the Power Control Message to each of the VMMs.
Any message will wake up the VMM(s) however the VMMs will not process any logic until it sees the Power Control Flag (specific PGN/SPN) telling it to process.