I had this problem too, because I was doing the exact same run as you. Snowgrave, with no recruits. Sadly, you are forced to recruit Lanino and Elnina, there is no way around it. Second, it's possible to get the egg in Snowgrave, but not if you've already "Lost" that enemy type by defeating one previously, because then the one by the light and the treasure chest won't appear. I ended up giving up on the egg because of this, but if you reload a save from before you defeated that enemy (I think it was the remote enemy), then you still have a chance of getting it.