I'm looking to delve into Blackreach with as many Dawnguard followers as possible, but I don't want a follower mod that adds a whole load of extraneous stuff (and will be problematic to uninstall as a result). So I've decided to allow myself up to ten followers, but I've hit a snag. I edited the dialogue conditions, they work fine. I also edited the follower script to increment the follower global variable rather than setting it to 1 or 0. But my previous follower still leaves my service when I recruit another.

Where's the secret?