Setting an ERPM limit for one motor based off another motors ERPM

It would be very useful for people using vesc for ebikes to be able to limit the RPM of a motor with reference to another motor's erpm. I've added a direct drive rear hub motor to a mid drive ebike and connected the vesc via canbus but, in higher gears the direct drive motor is being overspun and acting like a brake. I've also gotten overvoltage errors from the back emf I think. Being able to limit the Mid drives rpm when the hub motor is near it's maximum rpm would allow me to use the whole rpm range in low gears like 1 and 2 with out overspinning the hub motor in gears 6 and 7. Potentially this feature could be useful in other aplications as well.