1 Campaign, 2 Parties, 3 SAME PLAYERS.

[Doppã]

For Simplicity sake, each letter is a specific player, and each number connected to the letter is a specific character they played. There are 3 players, A, B and C.

Campaign started with
A1, B1 and C1.

As of now, we have are
A2, B1 and C2

A1 died and C1 ended up separated from the group.

Thing is A1 will be resurrected, and instead of discarding A2 or finishing his character arc too abruptly (which would be understandable, but still bad for the story) I thought of separating these PCs into GROUPS (Allowing them to fully play PCs they couldn’t do before is also a major reason).

GROUP 1:
A1, B1, C2

GROUP 2:
A2, B2 (new character), C1

The Setting is an enormous megadungeon overlapped by various systems of caves, it connects the world, meaning it’s an incredibly fast way of traveling, but dangerous.
This is essentially gming the same campaign for two tables of the same people, and some events taken in a group may affect the other.

A SESSION would be EITHER of GROUP 1 OR of GROUP 2, players would NEVER PLAY 2 PCs AT THE SAME TIME.
The campaign will be basically over by when they reunite.

What I need are insights. Mostly on concerns I should have in mind and opportunities it gives.

I have intention of limiting communications between GROUPS 1 and 2.
The players are aware that they will control 2 PCs in different places. I told them a year ago.
Medieval High Fantasy, TL3.