So I wanted to send some settlers from empty settlements to the Castle, which is my main settlement. The problem is the option to move them there is grayed out. I read something about charisma affecting the number of settlers, like 10+charisma level is how many settlers can be there. That's confusing, though. My charisma level is 6, but 17 people are at Castle, and some of my armor has 1-2 charisma bonus on it, making my charisma somewhere around 11. How does it all work??
You are correct when you say that your Charisma stat affects the number of settlers that a settlement can house. From the Wiki:
Each settlement has a default max population of 10 settlers plus each point of Charisma the character has, which has a base max of 21 before factoring in extra charisma from armor and consumables.
Therefore, what you said about having 6 points of Charisma, plus 1 or 2 points that are given by armor adds up.
Base Bonus + Charisma + Armor/Misc Modifiers = Total Max Settler Population 10 + 6 + 1 = 17
17 was the number that you said your population count is at, so that adds up correctly. (Note: it is also possible that you do not have any more beds for people to sleep in, which may prevent them from going to that settlement. Make sure you have enough.)
Thus, if you want to have more people in in your settlement, I recommend:
- Adding Perk Points to your Charisma stat
- Getting Armor that buffs your Charisma stat
Alternatively, if you want to go for maximum Settlers, check out this question.