They are my favourites too, athough these days with my tiny garden I can only grow a couple in containers. I've not grown them from seed so perhaps others could comment on that, but you could certainly divide them, especially if you have a fairly large plant. You could also try mail order if there are particular varieties you like.
Do you have any photos of your plants that you could share? There are some lovely newer varieties with more unusual colouring. I have Toffee Nosed which is gorgeous, and I like the green/yellow ones.
Best wishes and good luck!
