How many Ship Roles can one character cover?

Question

In the book Into the Storm for Rogue Trader, on page 225, Ship Roles are introduced. There is a lot of overlap between different roles, and I'm wondering how many roles can a single character have? Is it up to the GM? I've read that section several times, but I haven't found anything explicitly stating the suggested number of roles someone can have.

The genesis of the question is that Ship Roles have a direct effect on a player's skill-set. There are 22 Ship Roles separated into Ranks 1-4 (most important to least important) with 1, 3, 8, 10 being the respective number of roles in each rank. Each role provides both a role-playing consequence and a mechanical benefit. For example, if a player decides to be the ship's Master-at-Arms:

The Master-at-Arms gains a +10 bonus to the Prepare to Repel Boarders! Extended Action.

In addition, the player gains a role-player consequence of that role:

Each Role brings with it the benefits and obligations of rank: subordinates who will accept orders, but whose well-being and protection is an obligation, the recognition of the Rogue Trader’s dynasty, and a pledge of fealty that may require much toil to uphold.

Several of these roles overlap, usually between different ranks. It makes sense from a role-playing perspective to allow for one person to fill several roles (i.e. the group's Arch-militant would be well suited to be the ship's Master-at-Arms and Master of Ordinance), but I'm relatively new to Rogue Trader and don't want to unintentionally upset game balance by allowing players to take multiple roles.

Solutions that I see as viable:

1) Have each player take a single role. There are only five PCs, so there would be a plethora of NPC ship roles filled.

2) Have each player take several roles, with each career taking roles as appropriate.

3) Allow players to take multiple roles, but players cannot have more roles than another (if the Arch-militant has the fewest roles with two, then the other members of the group can have two ship roles each).

Since the ranks designate the relative position in a hierarchy and don't appear to significantly affect the mechanical benefit of each role I'm inclined to use my third solution.

Answer 1

I've played a little Rogue Trader, but am familiar with these ideas, and role playing in a hierarchy. Which is why I would honestly advise solution one, for a few reasons.

Firstly, there may be some 'geographic' challenge to having your Arch-militant fill both the roles of Master-at-Arms and Master of Ordinance. The barracks might not be located near the munitions depo or weapon batteries, meaning a guy who needs to command respect has to be running around the ship.

Secondly, hierarchy tends to get confusing when dealing with someone you both outrank and outranks you. If you don't believe me, go back to Catch 22 to, and reread the chapter where Major Major Major went to basic+officer training.

Thirdly, Nothing says hierarchy and displays the scope of the ship the PCs are living upon like recognizable NPCs whose primary job it is to preform one management task for the PCs... If the PCs are playing the main character's of M.A.S.H.; it's Radio who makes it feel like they are commanding a vast hierarchy, and not just a teeming horde in a space ship.

Lastly, and perhaps most compellingly; How can you have one of their underlings betray them if you don't force them into a position where they must trust some NPCs?