Folks wanted to finish out the quest from this perspective, so I'll fill us in on how that went.
Because one of the two hobbits gandalf has goes and grabs Saruman's orb, and that thing had a live connection to Sauron who is now psychically interrogating him
But the hobbit got lucky and the orb gets pulled away quick, and all Sauron got was a glance at Aragorn. Now: Sauron's a snob. he doesn't get hobbits or much care about them. All he knows is, a hobbit had the ring, Saruman's last report was that he captured a hobbit, and now here Sauron is seeing Saruman's orb making a psychic butt dial, by a hobbit, who is now hanging out with the Rightful King Of Man.
So Gandalf realizes that Sauron put two and two together, and got the *wrong* two's. Sauron thinks Aragorn came and liberated the hobbit to steal the ring that Saruman thought those hobbits had, and now he - being a mere man claiming The Ring Of Power - was preparing to square off for control of it. Great! Sauron can work this situation, corrupting the hearts of men to self destructive foolishness is one of the things his ring does best.
So if you're Gandalf, you tell Aragorn here to ham it up a bit, because the whole fate of the world now relies on successfully pulling a bait-and-switch about how many hobbits you had and which ones were which. They're sneaky, tricksy creatures when they need to be, so reports were probably pretty murky about them and odds are Sauron figured you brought three of them as decoys, because Sauron really just Does Not Get It. But you need The Unblinking Eye looking here and not under its nonexistent nose.
Meanwhile: your two original Hobbits are off infiltrating Mordor. You get some magic intel on them every now and then, but not much. You have no way of telling them to Absolutely Under No Circumstances Go Into The Spider Tunnel, but turns out, Spider Tunnel is in fact a two-hobbit problem.
In fact the gardener has a real way of turning things into one-hobbit problems. After the spider tunnel he goes on a little bit of a rampage sewing chaos behind enemy lines, and of course the armies of Sauron Don't Get It any more than their boss does, so they think it's some ages-old Elf super soldier infiltrating the fortress - only making it easier for the two short halflings to make their escape.
Meanwhile the hobbit you've got with you, who you told to keep his mouth shut, goes and swears an oath of loyalty to the Steward of Gondor. But that DOES turn out pretty well, because now he's got access to some places where it really pays to have eyes and ears. Really the longer you spend with these hobbits the more things tend to boil down to being some-number-of-hobbit problems, you really lucked out getting four of them in play.
Meanwhile though your two key hobbits are scaling Mount Doom - you don't know this in the moment, you only hear about it later - but it turns out that The Ring Of Power is a tough one. Two-hobbit problem to get it to Mount Doom, but whether it's because The Ring upped its game or the ringbearer finally broke, throwing the damn thing into the fire was too much for the pair to manage. It stops the bearer short, mere feet from victory.
Enter the third hobbit in Mordor, an old, pitiful, decrepit thing who's only a hobbit by technicality at this point, who happens to fumble his own gambit for it in exactly such a way as to finish the job and save all of Middle Earth from Sauron's influence.
You're hearing this, perhaps, over a victory feast, realizing you were wrong from the start and in fact never grasped it until just now. This was not a two-hobbits problem, nor, in fact, a four-hobbits problem. It took five.
