For your amusement while you wait to hear if your theory rules, here's a summary of how the Swedish swap was implemented in the German version last year. If that's the theory tonight, it could be useful. If not, it's amusing.

I surfed the net looking for rules or episode summaries of the Swedish version unsuccessfully, but found a German language site for the German/Austrian 2000 game with a day by day (almost 50 days) account of what happened in each camp. I read German to an extent, so I was able to find the swap. Then I ran the 3 days through a translation engine with some success, and edited out a lot of narrative about camp life to focus on the game.
(I left some in because it was amusing. Note that they refer to the Fire as a "workstation" and to booting as "logging-off" a contestant, which I found pretty funny.)

My Summary followed by translation below.
Setup:
Two teams, German and Austrian.

1st day: Teams choose a player from the other team to come over: the Agent. Choose one of their own as Ambassador.
Teams backpack to a hut somewhere and exchange Agents and return to camp.
Germans pick Birgit (Agent) from the Austrians and make Marcus their Ambassador.
Austrians pick Marc (Agent) from the Germans and Maria is Ambassador.
Note genders are not the same. Not clear what is ambassador's role.

2nd Day: Reward challenge won by Austrians, durian fruit and fish.
One of German team (Nico) volunteers to leave--QUITS. Check out his reasons!
The Austrian team gets a brand new player (Ulrike/Uli) as the replacement. Now there's a twist for you.

3rd Day: Competition for the Robinsonspiel (IC). Agents and new player sit out. Austrians win.
Germans go to "Island Advice" (TC) and vote out Gaby.

Interesting to me, the players spend some time discussing past voting but not much time conniving for the future (at least not in summary). No alliances are mentioned, so it's hard to tell what happens politically with the swap. The Agent (swapee) does not compete in team IC, unlike in Swedish "hostage" version.
The Austrian agent (Brigit) seems to feel she's next, but the German swap (Marc) seems to settle right in. Also, people sleep in and no one rags on them. Island life is not so stressful as Africa.

TRANSCRIPT-- (words in parentheses my translation where Alta Vista engine failed. Bold highlights my emphasis.)

Day 13
(German Camp)
THE AGENT EXCHANGE.
Each group must select an exchange agent from the opposing series. The German team packs its backpacks and sits afterwards in the hut and waits for the exchange. Marcus will be an Ambassador. They discuss the selection of the agent. Finally Birgit from the Austrian group is selected. The agent exchange takes place. The team returns with Birgit to the Camp.

(Austrian Camp)
THE AGENT EXCHANGE. All sit at the stock pile. The name of the selected agent ' Marc ' is written on the note. Maria is determined as an ambassador. The backpacks are packed: Abmarsch (March away). They return with Marc as agent.
(New kid in camp interacts)
Marc inquires, how much meals have the Austrians still. Otis tells etc. of the staggered array, of fishing. Maria explains that there is only breakfast and dinner, but no lunch. Franz opens a coconut for the celebration of the daily. They converse about it, why Stefan and Gerhard in the island advice were voted out. Marc asks for the reasons for the logging-off of Andrea. Marc reports of the German team.

Day14
(German Camp)
NICO VOLUNTEERS TO LEAVE THE ISLAND.
Nico has no more strength, as he says. Two weeks are a mad performance for him. ... . He wants home, needs cleanliness, meal of Mami and the Parties. Nico requires all much luck and hopes that Thommy or Marc Robinson 2000 become. Everything sings to him a song, embrace themselves, heart pain scenes. Nico snatches his backpack and goes the last steps alone to the beach and rises in the boat. The boat drives off, he signs, the others cry and sign also, until the boat is not to be seen no more

Day 14
(Austrian Camp)
THE SECOND DAY WITH ' AGENT ' MARC.
Marc is a Langschlaefer. (Late sleeper). Then also he wakes up and comes out. He sits down to the others to the fire workstation. Breakfast. Puzzle together all that for a weekday is today. The group goes to the price play and wins. (REWARD CHALLENGE) As gain they receive a fish and a Dorian. Hardly one (except Otis) is so correctly inspired by the fish. But all have hunger.

Day15
Austrian camp) THE ROBINSONSPIEL IS WON. (IC)
(Left rudely translated because I think it's funny.)
All branch out of the boat and run loud jubilant with their battle call in the Camp. Otis told, he is actually no good float and would have been glad that it also something would have given to climb! Franz is rather something angeknackst that he could not contribute to the victory. But it goennt Otis the triumph. He means only: I would also gladly have made it. But I feel so weak as if I would today have swum.
Uli and Marc sit at the fire workstation. Uli tries to cut a piece out coconut. It creates it however not and transfers the coconut at Marc. Otis is added and gives to Marc a small scooter (in size of a surprise egg scooter). " that gave you the sea ". Later Marc tells of its first age-old Vespa, which he probably drove with 16 and on which he was powerfully proud. There also today again no fish imprisoned became to cook it a root and eat at fire workstation. Uli runs down to the beach, in order to get Franz to the meal. He jumps up and calls: " Hey, that is like at home with mummy: Meal is finished. Franz come! "

(German Camp)
GABY IS VOTED OUT IN THE ISLAND ADVICE.(TC)
The team pulls itself over for the Robinson play and marches with statue and flag loosely. Agentin Birgit remains in the Camp. As later all again tell they return Birgit like the play ran. Birgit is sad that she cannot celebrate the victory with her team. All, except Marcus sit and are because of the beach and speak briefly about the island advice. He finds the tendency amusing, he feels simply bad. Birgit believes that she is rausgewaehlt (probably "out of there") next time. It is spoken also about the new one in the Camp south (Austrian). After the island advice in the Gaby turns the German team was voted out back in the Camp. (Convoluted, but it appears Germans voted out Gaby). They sit all around the fire place and say nothing, stare before itself.
----------------------------

It Can't Happen Here"--Zappa