I found a griz brought in nesivas hakodesh on menachos 34a dh veha that asks from the mishna in brachos that an eved kenani is chayav in mezuza. how can that be. the gemara is mevuar that it is a chovas hasocher v’ain kinyan l’eved . so he answers The chiyuv is not talui in his kinyan in the huse. It is talui on for whom the house was meyuchad for. so even if it is only for avadim they are a dweller and will be mechayav in mezuza
for a full cover on this sugya ( chiyuv on socher) look in the mesivta in otzar iyunim maareches 17 .1 .2