DISCLAIMER.
OK, I admit they are not lore-friendly. (Why couldn't they have sisters or something though?). The idea was primarily functional - I ran out of female companions with extended dialogue while re-playing the game, as well as technical - an attempt to make plausibly sounding female voices out of male ones.
DESCRIPTION.
Hancock's original ghoul voice has led me to creating a fairly exotic character who IMHO fits with the resulting voice quite nicely. I used the MiscHairstyle 1.6 by Atherisz mod. There is some hair clipping when she is wearing her tricorn hat, but the "Shaggy" haircut still seems to be the best overall character match.
MacCready's appearance is less critical. Any womanly kind-looking preset should work fine.
REQUIREMENTS AND COMPATIBILITY
To look the same as in the images the mods will need the above mentioned MiscHairstyle1.6 mod. Please google and download it from Tumblr as it is not allowed to post direct links to external resources here. No other additional mods are required. None should be incompatible either (except for ones that in any way modify those NPCs).
If you don't like the suggested companions' looks, you can easily change them in-game, either manually or by using LooksMenu presets. There are quite a few cool ones available here on Nexus. Please note that if you are using the Female Hancock Ghoul version you would need a female GHOUL preset for Hancock.
The new voices sample video was kindly provided by Sephrajin.
INSTALLATION.
Make sure you have made all the necessary configurations to enable mods in Fallout 4. If you haven't done this yet, check out the Fallout 4 Mod Installation tutorial.
Manually download the mod file(s) you need and use the NMM to install or uninstall both mods.
WARNING.
After installing or uninstalling these mods you should start a new game. Using old savegames (saved after you first met Hancock and MacCready in Goodneighbor) will mess-up their appearance irrecoverably.
You can try resetting the companions by using console commands: select the companion's reference (click on companion in console mode) and type recycleactor (Enter), followed by moveto player (Enter) then type resurrect (Enter). Remove all the companion's inventory before doing that.
CREDITS.
To Sephrajin - for the voices sample video.
To Jinamaja - for the transgender idea.
To Asterra - for the voice change idea.