Complex sentence: Realizing Doug can take care of himself now, the three clones move away, later writing Doug that they have set up a successful pizzeria called "Three Guys from Nowhere" in Miami, Florida.
Split into simpler sentences: Realizing Doug can take care of himself now, the three clones move away. The clones write to Doug that they have set up a successful pizzeria called "Three Guys from Nowhere" in Miami, Florida.