That's how it works if you've never assigned them to a settlement. I have no idea if it still works that way if you did before. I would like the option to send say 2 or 3 to Home plate tho. Maybe more if there was some simple way to build on your roof. Or possibly a mod that adds a basement floor?? Something tells me this'll happen. Everyone keeps posting the same "solution" over and over and people keep repeating over and over that it does not work if you already sent them to a settlement before. If I knew at the beginning of the game that pressing B in the menu, closing it without assigning them to a settlement, would make them go to their original homes, I would have done it. I thought I was forced to choose, and thinking that later I could just tell them to go to another location like Diamond City or whatever else, I did.