I've found that to make the entourage system work, each NPC only needs about one or two scenes with the party. Thereafter, they can appear briefly and a very short scene and everyone sort of understands that they are there. More on this later.
Ishi - Planetary Expert
Picked up on Footfall as a consultant
Background: Ishi is a planetary expert - a dedicated explorer and soldier of fortune who has seen dirtside on countless worlds. Ishi grew up, hand-crafted by a guild of explorers. From the time she was a little girl, she was taught the way of her guild's explorations and techniques. However, her guild was long ago wiped out by the insidious actions of a xenos cult. Since that incident, much of her memory has been wiped out, for in her escape, her ship was lost in the warp for a time. Since her memory loss, she has made a name and life for herself exploring the fringe. Ishi's actual age is unknown to most. She appears to be a young woman but often hints at a past which stretches back at least a century.
Personality: Calm; curious; and wise
Represents: Ishi is an expert planetary explorer, but does not actually represent any crew population. The planetary explorers are represented by Brother Vhist.
Incabula - Second Navigator
Picked up on the Angevin's Blade, when the Explorers reclaimed the derelict vessel
Background: Incabula is a navigator with one of the great Nomadic Houses. The circumstances of her joining with the ship Angevin's Blade is not entirely clear, but it is believed that she was purchased with a number of other navigators for the small but significant Baetarn Merchant House. If the records are to be believed, the Angevin's Blade was a guardian vessel for a trade fleet which is now presumed lost to ork attack. It is unclear how precisely her ship was overtaken by orks. She is loathe to speak on the matter and it may be that she does not even rightly remember all of the details. Her mind has blocked portions of the details out.
As the navigator of a guard vessel, Incabula specializes in monitoring and watching the Warp. She seems to be a capable navigator, if a little touched in the head.
Personality: Distracted; blunt; and unhinged
Represents: Incabula represents the navigator and entourage of the Angevin's Blade.
Lieutenant Ergan Wright - Lead of the Remaining Crew of Lucien's Folly
Picked up when the crew of the Lucien's Folly was rescued from the Cauldron
Background: Ergan Wright is the last remaining member of the command structure of Lucien's Folly - an exploration frigate that was lost to the Cauldron in the Koronus Expanse. Ergan is a seasoned officer, who has seen many trials and tribulations as the leader aboard a free trading and exploration vessel. However, his commanders bit off more than they could chew when they went to the Koronus Expanse. Wright's men are utterly loyal to him. There is a special bond between all of the surviving members of the now-perished Lucien's Folly.
Personality: Haunted; grizzled; and stoic
Represents: Ergan Wright represents the crew members that are survivors of the Lucien's Folly - approximately 12,000 men and women in the Rogue Trader dynasty.