For what it is worth, I rooted a Dwarf Cavendish pup with less corm than
your pups. I left only the emerging-leaf on the plant, pushed it a bit in normal
potting-soil, supported it with sticks so it could not fall over and watered just a tiny bit. As it has no roots it can't do anything with the water but it came to life.
Have to say I did this immediately after seperating the pup and yours have
been on their way for some days I assume, don't know if that makes a difference.
So there is hope, but it won't be easy
Ron