If all of your settlements are at maximum capacity for settlers where does your companion go if you get a new one and dismiss the old one? I'm afraid to even try it. All my settlements are max capacity except for Boston Airport, which isn't even really mine and I've read that companions can get stuck inside the geometry if they're sent there.

Boost your charisma by drinking beer or wear charisma boosting clothes or take charisma boosting drugs or execute a settler.

Thank you.