When the babies are ready to come out and they are reluctant, the dad will boot them. I used to net the cave with dad and eggs-wigglers and move them to a smaller tank with less decor. This becomes a ready made grow tank for the kids when he does and it will make the offsrping easier to catch when you have to move them to new homes. When you return dad and cave it is helpful; if the cave goes back in the same spot from which it was taken.
One note here. I had spawning BN for about 8 years before I moved all of them out. While my first spawns numbered in the 15-25 range. when I got my final spawn from my last pair, it was over 100 fry. Just andFYI- as the fish grow, the females produce ever larger batches of eggs.