Sure, that's definitely possible. Since i use identical burners for my HLT, MLT, and BK, I only need to adjust the regulator once, and when the flame is dialed in on one burner, it's dialed on all 3 and rarely needs adjustment. In your case, getting all three burners dialed in is going to take one extra step or one extra part.
It you've got 10" burners under your HLT and BK are going to have orifices that require higher pressures (somewhere <30 psi) than the 6" burner (<10 psi). The effect of this will be that when you've dialed in your 10" burners, the pressure will be way too high for your 6" burner. To correct this, you've got two choices -
1) install a needle valve between the MLT ball valve (ball valves are basically on/off switches, which you'll need, but they're not good for making adjustments) and the 6" burner orifice. A needle valve will allow you to actually make adjustments
Or
2) slowly and incrementally increase the size of the 10" burner orifices until they operate efficiently at the same pressure as the 6" burner. To do this you'll need to find the orifice size/drill size chart. There are a bunch of HBT threads discussing orifice size, so browse through them and I'm sure you'll find it + other helpful info.