If it's a direct continuation, my opinion is that it would seem more convenient to have them all in the same pool, but explain in the pool's description.
Eh. Different titles, different focuses, and the prequel is already its own pool. I prefer that the pools stay separate, with links to the other pools in the description like in pool #2360. Merging sequential pools doesn't sound like a good habit to get into. Granted, "merged" is how it started out, but still.
If it's a direct continuation with no change other than the title I see zero reason to split the pools unless they're manga-form and have their own cover pages/closing pages.