I suggest Tighten the plot by dropping the yacht, so that there is one goal. Make the yacht recovery the next scenario, a la the above suggestions. week and months of repairs, etc. S they will not be able to use it as a resource, until the major/ minor deal blows over.
Make the search for the Minor Noble the main goal.
Give them a timeclock, such that they have X weeks to find this guy or...an option clock such that they run out of places to look for the minor noble. The last place they look is where he is, with interesting stuff happening along the way.
Perhaps the rebels have him, and he is under lock and key, for whatever reason, perhaps kidnapped, and Major noble wants to avoid paying the ransom, but does not want to involve the authorites, because he's got some kind of legal trouble, or underhanded dealings a la the crime lord guy, and doesn't want ANY authorities on the scene.
OR
The Major noble is in charge of some gigantic megacorp deal, that is scheduled to go down in X weeks. The thing is, it's a swindle, more or less, but the Minor noble has insider information, that the major noble doesn't want to get out. After the deal is done, though it's too late. layers of intrigue.. the minor noble thinks he's been kidnapped, for some kind of ransom. The major noble has contracted a bunch of mercs to do it, with a small payment up front, to hold him, and a major payoff on delivery.
But in reality, the major noble is gonna write off the mercs, hoping the get killed in the "Rescue" by the PCs, perhaps aided by the local constabulary after the deadline of the big sale has passed. They were told to sit tight on the guy and release him after X days, to get passage offplanet, and a big bank payout. But really Major noble is sending in the PCs to kill them, and make himself look good as the rescuer, who sent these trouble shooters in.
This could even be set up such that through a trail of dummy corps nobody can ever really find out that Major noble was the big profiteer.
OR
Minor noble is missing because he's been in the sack with Major noble's wife. After the pcs find minor, major will send in a hit team (who follows the pcs and spies on them, as soon as they hit the target world, tipped off by Major) to bag him / AND / or the wife, too, if the Major guy is really hard core.
Perhaps minor noble absconded with Major's drug stash, or some kind of priceless (and also Stolen) art work. Minor can't find a fence, because they are all in the pay of major, as a large theft ring, with him as the financier.
OR
Making it a more pleasant scenario, the Minor noble is the Major noble's bastard son. He wants to find the kid to reward him with a NEW yacht, the old one the pcs get was bought when the kid was a child, as his inheritance upon majority. Well, that was 20 years ago, and it's fallen into disrepair, or new technology has developed since then, and only the best for this major nobles kid, even if he is out of wedlock (Because, perhaps, he's married to a gal in some major line or house. The kid is missing because he's paranoid. Guys in suits came after him on the street, and he's got some kind of mental disorder, and is thinking all kinds of stuff.
So he's in hiding, and paranoid, thinking they are out to get him.
OR
The whole thing is a scam. It's a training course by their intel services, as a test to see if the "minor noble" can keep himself hidden for X weeks, as his "Graduation project," to go active in some kind of covert ops program, in a safer way than just dropping him off in enemy territory.
OR
The whole thing is a scam, a giant game of hide and seek among the nobility, with the prize as 1 Mcr, they take turns doing this crap every year, and always need to find fresh teams, because the low pay or whatever isn't worth the hassle.
OR
Minor noble has committed a crime, so heinous, he doesn't want to get found out, and thus ran, and his father / uncle / whatever doesn't want the police or authorities involved, let alone the media. The pcs will find out what the minor has done just prior to finding him.
OR
The reverse, the minor knows what dad / uncle is up to, and is on the run from his assassins. the team is just a back up. The pcs find out about the hit team, just prior to finding minor. The he tells the story, and they have to decide if they believe him or not, while the door suddenly come blown in by frame charges and flash bangs in the room. Kind of a cyberpunk feel.
Best of luck with it.
