The MCs aka Joseph and Hannah will be Using each others Names but when interacting with other like them if they find anyone else EG they find a Scout Marine of the Dark Angels they would call him Chapter-Master X of the Dark Angels and he would say Fabricator-General Hannah or Lord Commander Militant Joseph.

Due to being 'Living' Members of they respective groups in the lore anyone they Summon like in Cp3 with the 2 PDF they called Joseph Lord Commander Militant instead of Corporal or Sergeant, they will always Referee to them as the Highest Rank

[Full Names, Ranks and Ranks they had by the System]

Lord Commander Militant Joseph and Senior PDF CO Joseph

Fabricator-General Hannah and Junior Tech-Priest Hannah

Infantry Assets 

1 Psyker, Marcus (volunteer)

1 Vox Caster, Kagar

1 Unit Flagman, Luz

2 Guardsmen, Hans, Ralof

1 Senior Planet Defence Force NCO

3 Junior Planet Defence Force NCO, Hans, Ralof

4 Planet Defence Force Vet. Yet to do anything notable

9 Planet Defence Force, Yet to do anything notable

*Special*

2 PDFs Vince and Burt

1 Pre-Trial Space Marine Jeff

Armoured Assets 

"Fighting Girlfriend"  a Chimera built with a Turret that has Autocannon and Co-axial Heavy Stubber and a Hull Storm Bolter and Her crew Commander Lucy and the others have Yet to do anything notable

[Joseph's Status]
Name: Joseph
Rank: Senior Planetary Defence Force CO [Called Rank Lord Commander Militant]
Level 8: 37 kills till leveling up
Allowed Weapons: Las-Pistol, Krak Grenade, Frag Grenade, Chainsword
Allowed Armor: Medium Flak Armor, standard Junior PDF CO Dress
Allowed Vehicles: 1/2 Chimera(Hull Bolter)
Allowed Command: 20/20 [Open Choices]

[Hannah's Status]
Name: Hannah
Rank: Junior Tech-Priest [Called Rank Fabricator-General]
Level 3: 3 Kills or appease 3 machine Spirits
Allowed Weapons: Las-Pistol, Machanicus Blade
Allowed Armor: Light Flak Armor, Senior Acolyte Robes of the Machanicus
Allowed Vehicles: None
Allowed Command: 4/4 [Open Choices]
Augmentations: 2 Mechadendrite, 2 Audio sensory enhancers
[Vice-Leader of Regiment of Guard called the Terran Old Guard]

[Marcus's Status]
Name: Marcus Marjewl
Rank: Senior Sanctionite [Beta]
Level 2: 5 kills till leveling up or use Psychic Shriek on a Enemy
Allowed Weapons: Las-Pistol, Sword
Allowed Armor: Light Flak Armor, Psyker Robes [Update Dress]
Has Powers: Telekinetic Shield, Psychic Shriek
[Volunteer Member of the Terran Old Guard]

Entry one on this World System,

I know to little to make a note but what my theory is that their must be that a large maybe 75 to 90% of the Population that can't use it.