IRP notation: {35.7k}<308,-881|669,-520>(2072,-484,F:2,D:3,C:4,-2300)+
C is reported as SubDevice. It is probably a check nibble {C = F*4 + D + 3}.
F = 1 for UP or 2 for DOWN.
D = 1, 2 or 3 for the three observed devices, or D = 0 to control all devices together.