Cleon
Legend
We seem to have some freedom there. The simplest thing to do would probably be to make a single swarm that takes up a large space along with a really big slug (even sporocarp). However, the swarm rules only allow a 10 ft space, and the variation of magical power might argue for X independent swarms with a group hive mind, where X=30 at present.
I'm leaning towards some kind of gestalt hive-mind approach, but it might become a bit complicated.