Is my immigration policy going to haunt me?

I've decided to wall off my fortress with my initial seven dwarfs and bar all access from the outside. The immigrants will be denied entrance and will eventually die outside to hunger, sieges or wild capybaras. Since I don't plan on going outside, will they eventually return as ghosts?

I ask because A] if true, I can simply build a memorial slab for each ghost (tiresome), B] I think the ghosts need someone they know to haunt, which won't be true in the case of a mass slaughter of immigrants.

Solution 1:

Yes, your dwarves have a chance to return as ghosts no matter how they die. They do not need a particular target, and will simply wander through your fortress causing mischief, destruction, and death, although it is possible that some of the more dangerous ghost types require certain types of deaths. In conclusion, yes, you will need to build a memorial slab for each ghost.