Hi,
Welcome to the forum!
Consider this: when stacking these pedals, the idea is that the one that comes last before your amp will have the most dominant character, while retaining flavors and feelings of the one(s) you put before it. So if you put your HBOD last in the chain, then you will still have the overall sonic footprint of your HBOD, seasoned with whatever you feed into it. You could use either drive pedal (DRD or EGDM) to drive your HBOD even further. What you will likely get is a sound "shaped" similar to the HBOD by itself, but with more gain and compression. But the sound will still have much of the basic "shape" of the HBOD.
If you try the reverse, say with the DRD, you can set the DRD to the nice crunch tone you like. If you would like "more" of that, then you can use HBOD to thicken the gain even more, while still retaining much of the basic character of the DRD.
It helps if you think of these pedals as little "pre-amps" and "power-amps," the same way you would think of gain stages in your amplifier.
It also helps to know what kind of guitars and amps you use, and to what sonic objective.
With a cleaner amp, it would be my personal preference to run:
Guitar > HBOD > EGDM > DRD > Amp,
because then you are increasing the order of magnitude of distortion capabilities as you approach the input of your amplifier. With DRD being the highest gain of the bunch, you can run that by itself. Or you can set things really low on it, then add flavors of HBOD and/or EGDM into DRD on its way to your amp. Overdrive (LGW, HBOD, etc.) > DRD is a particularly ferocious guitar hero sound.
But running things backwards from what I just described will also produce unique and fun sounds in their own right. It's a question of personal preference, and my thought is that you are going to need to tear apart your board and play around with all possible combinations and use your ears to find what will most inspiring to you.
Have fun!!!
Doc
Get in where you fit in.