It’s really easy to to divide and propagate Brunnera macrophylla. To quickly get new plats from an existing split the plant in two while still in the ground, dig up one of the two halves and re-plant it somewhere else.
Step 1: Separate the leaves into two groups
Step 2: Use a shovel to dig down in the middle and split the plant in two
Step 3: Dig up on one of the halves
Make sure that both halves have healthy roots!
If you want to be extra sure the roots are ok, dig up the whole plant before splitting it. It’s an extra step that allows you to see where the roots are and where to best make the split. While adding extra control it’s a bit more work and I find that in most cases the plants do fine without it.