sand boa and frozen thawed

i have about 30 subadult Kenyan sand boa that i, regrettably, didn't get switched to FT food when they were babies. now that they are getting bigger, big enough to eat hopper mice, im afraid of the mice hurting them. i have 3 switched over but the rest wont make the switch, anyone know if scenting or using large deli cupping would help them along?
thanks:snake:

i recently read that some well known breeders use paper bags and let them stay inthere over night together with the prey(ft or alive) and that seems to work in most cases
scenting should also work but all depends on the animal